[GMCnet] Tires

[fluffyms]

Am having a mind freeze....(which seems to be occurring more frequently lately (lol).

My coach is currently running on 16.5" radials, with the original steel wheels.

Sometime real soon, I plan to get either the Alcoa's or Eagle's,. Haven't really decided which although it's my understanding that Jim K. will have Eagle's "on sale" during the month of December.

Anyway, my question is - Going to a 16" wheel/tire, from a 16.5", how will that effect the speedometer reading???

I should know this, but as I said earlier, I'm having a mind freeze.

Anyone have any thoughts??

Thanks,

Steve Nowak
F26083
'78 Royale Center Kitchen
TZE368V10877

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[Ken Burton]

It has no effect. If you use the correct size tires, the revolutions per mile on the new 16's are the same as your old 16.5 tires.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

[Roger P. Gleason]

First of I purchased my coach with Eagles and new tires LT225/75R16. This seemed to be the same size tire that I seen everyone else with Alcoa's or Eagles have used, so I gave no thought to changing tire size. With some background in automobiles I did take the difference into consideration when making alignment calculations. I have a 71 GMC pickup with the original 16.5 rims and high profile tires like original equipment. The tires on the motorhome are a little over 1 1/2" shorter than the tires on the pickup. Dividing this number in half the motorhome will set 3/4" lower than it did with original equipment tires. I took this into consideration when making height adjustments.

Now to answer your question, for the reasons above I questioned the speedometer along with the fact that my GPS registered faster speeds than my speedometer did (this is usually just the opsite in a vehicle with an accurate speedometer. The difference is due to the GPS registering topical speed verses the speedometer registering land speed (hills). We have a turnpike in the State in which I live that is just ove 100 miles from one end to the other. I checked the speedometer/odometer over this 100 miles finding the motorhome speedometer/odometer was registering 7% less than actual.

I believe this difference is due to the smaller tire and wheel size.

Hope this helps.

[Mr.erf ERFisher]

here is some info
http://gmcmotorhome.info/tires.html

gene

--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html

[Don Adams]

I have a question for some of you guys who have been here a long while. Any one heard of guys going to 9.5 x 16.5 tires?

"The new direction is to use 16 inch wheels" Was the old "new" to use larger tires to try for better mileage?

I am looking at a Palm Beach with 9.? something tires, 9.5 I think. Both the middle and rear tires are just about touching the T skirt. I bet its a bear to get that sucker moving.

I also wonder why no one mentions going to a wider wheel, availability I guess. Jim K mentioned one time he was looking at 17" wheels. Your favorite BFG TA's are available in 17" diameter. Sure would like some 17 x 8" wide wheels.

--
Don

- 67 Datsun 2000

- 78 Suzuki 400

[Roger P. Gleason]

I am not dead sure as to why GM choose 16.5. Gm, Ford, and Crysler all used the same 8 bolt pattern, Ford and Crysler chose to use 16". The problem created is the 16.5 tires are sometimes hard to find and they also sometime charge a premium for them. If you live in a big city its no problem, but if you are out in the middle of nowhere it can be.

[John Wright]

Don,
Bigger is not necessary better. The larger 9.50-16.5 E tire was a
larger size that did fit closely. As you go up in tire size you
affect your final drive ratio. The 3.07 gear is marginal for
everything except flat land driving. If you have the 9.50 tire on the
coach your ratio becomes a 2.98. The 8.75 tire was the stock size
that kept the ratio at 3.07 and 225/75R16E tire is a 3.06. I drove
the 3.07 for 1 year and it was a real dog and then switched to a Jim K
3.55. Really wakes the coach up. I run a 225 ragwall tire on the
drive axels and the new G147 all steel on the back. I have run all
steel, all ragwall and a combo of ragwall on the front and all steel
on the back. The all ragwall and the ragwall/steel combo rode the
best with the all steel the worst of the ride and steering. As for
brands everyone has there favorite. I have BF Goodrich Commercial T/A
on the 77 with balance beads and it is a great ride and steers great.
The 75 has the Goodyear LT225/75R16 LRE Wrangler HT ragwalls on the
front and the Goodyear G147 All steel on the back. It has no road
miles yet as the tire on cart. Most of the tire makers can supply an
acceptable tire that will work well with the coach, the choice is yours.

Here is the tire size drive ratio chart:

http://www.gmceast.com/technical/Brown_Drive_Tire_Ratios.pdf

J.R. Wright
GMC GreatLaker
TZE Zone Restorations
77 Eleganza Custom (For Sale)
1975 Avion (Under Reconstruction)
Michigan

>
> I have a question for some of you guys who have been here a long
> while. Any one heard of guys going to 9.5 x 16.5 tires?
>
> "The new direction is to use 16 inch wheels" Was the old "new" to
> use larger tires to try for better mileage?
>
> I am looking at a Palm Beach with 9.? something tires, 9.5 I think.
> Both the middle and rear tires are just about touching the T skirt.
> I bet its a bear to get that sucker moving.
>
> I also wonder why no one mentions going to a wider wheel,
> availability I guess. Jim K mentioned one time he was looking at
> 17" wheels. Your favorite BFG TA's are available in 17" diameter.
> Sure would like some 17 x 8" wide wheels.
>

> Don

[David L Greenberg]

On Sun, 22 Nov 2009 16:56:47 -0600 Roger P. Gleason <rgl...@peoplepc.com>
writes:

>
>
> I am not dead sure as to why GM choose 16.5.

It could have had something to do that the coach was built by the Truck &
Coach Division. I don't think GM provided much oversight on GM T & C.

David Lee Greenberg
Port St Lucie, FL
Dedicated to the Preservation of the Classic GMC Motorhome
http://GMCmhRegistry.com
48 Packard Super Eight http://www.picturetrail.com/gmcregistry
____________________________________________________________
Wholesale Hardwood Floors
Never pay retail again. Wholesale prices on all hardwood flooring!
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[Rick Denney]

fluffyms writes...

> Anyway, my question is - Going to a 16" wheel/tire, from a 16.5",
> how will that effect the speedometer reading???

The rolling diameter of one brand of 225/75R16 tires is 29.3", and
they will all be similar.

I tried to look up the rolling diameter of 8.75x16.5 tires, which were
the original size on the GMC, and I can't find any online tire
database that lists specifications for non-metric tires except for
high-flotation mud tires. Thus, I suspect it has become impossible or
nearly so to buy them. Your plan is a good one.

Nominally, the 8.75 tire has a 78% profile, so the rolling diameter
should be 30". That's 2.4% larger than the 225/75R16 tires--within
normal error range of the speedo anyway. The 245/75R16 tires are about
the same error in the other direction.

Rick "who has seen both 225 and 245 tires on GMCs, but most go with
225" Denney

'73 230 Ex-Glacier "Jaws"
Northern Virginia

[Rick Denney]

Roger P. Gleason writes...

> I have a 71 GMC pickup with the original 16.5 rims and high profile
> tires like original equipment. The tires on the motorhome are a
> little over 1 1/2" shorter than the tires on the pickup.

That difference should be 3/4" in the diameter. You must have had
9.5's on your truck. The original spec for GMCs was 8.75. Their 30"
rolling diameter is .6" larger than the 29.3" rolling diameter of
225's.

> ...I checked the speedometer/odometer over this 100 miles finding

> the motorhome speedometer/odometer was registering 7% less than
> actual.

> I believe this difference is due to the smaller tire and wheel size.

My speedo read high even when I was running OEM 8.75" tires. The old
mechanical speedometers of that era weren't necessarily all that
accurate, and +/- 5% is pretty common. I had a '74 GMC pickup with
stock tires that was more like 10% high.

The difference in nominal tire diameter is about 2.4% between
8.75/78R16.5 tires and 225/75R16 tires. That will cause the speed to
read 2.4% higher because the tire is making more revolutions in the
same distance. 245 tires are off in the other direction, but might
have helped correct what was already an error in your speedo.

The 245 tires will fit and I've seen them on coaches. They are about
1.2" taller (overall), and will come about .6" closer to
interferences. But I bought 225's because I didn't really want to
increase my gearing.

Rick "but the 245's will increase ground clearance by .6 inches"
Denney

'73 230 Ex-Glacier "Jaws"
Northern Virginia

_______________________________________________

[Rick Denney]

Don Adams writes...

> I also wonder why no one mentions going to a wider wheel,
> availability I guess. Jim K mentioned one time he was looking at
> 17" wheels. Your favorite BFG TA's are available in 17" diameter.
> Sure would like some 17 x 8" wide wheels.

This actually has been discussed quite a lot, but it has been a while.
You need two things to go to a wider tire: A wider wheel and a wider
tire that maintains an acceptable rolling diameter and doesn't run
into things. Jim Bounds has wider wheels on the front of Larry, but
his source for those wheels was good luck, not anything that is really
repeatable. They can be custom-welded, but then you have heavy steel
wheels. To go to a wider tire at the same rolling diameter, you need
tires with a lower profile that still have the weight rating, and when
we discussed this a year or two back nobody could identify the tires.
Maybe they are available now, but I bet they aren't cheap.

I would not be a fan of going to 17" wheels. Frankly, I think a tall
sidewall provides more compliance and absorbs more road texture. These
low-profile tires look nice to the modern eye, but they are hard on
the fillings. And I'm sure I will offend someone by expressing the
opinion that a pickup truck with 22" wheels and a layer of what must
be solid rubber over them looks really silly.

Taller and narrower tires also provide better economy and better
traction in the wet with less likelihood of hydroplaning. Low profile
tires have more hysteresis in the sidewalls (unless you run them at
higher pressures) and make more heat when not being driven at the
limit of adhesion.

Those wide, low-profile tires sure are nice in tight corners, though.
That isn't exactly the GMC's design envelope, however.

Rick "who enjoys paying a fraction of what the big RV owners pay for
tires" Denney

'73 230 Ex-Glacier "Jaws"
Northern Virginia

_______________________________________________

[dennis...@aol.com]

My thoughts are that the taller sidewall is beneficial on the rear of the GMC, especially a 23 ft, as the relatively short wheelbase with the tandem wheel set-up puts a lot of side force on the tires when "parking lot" turning. If you want a visual, start a sharp turn when parking and while the front wheels are still are max stop the coach, get out and look at the distortion on the rear tires/wheels.

Dennis

Dennis Sexton
73 GMC
Germantown, TN
USA

-----Original Message-----
From: Rick Denney <ri...@rickdenney.com>
To: Don Adams <gmc...@temp.gmcnet.org>
Sent: Mon, Nov 23, 2009 1:02 pm
Subject: Re: [GMCnet] Tires

Don Adams writes...
> I also wonder why no one mentions going to a wider wheel,
availability I guess. Jim K mentioned one time he was looking at
17" wheels. Your favorite BFG TA's are available in 17" diameter.
Sure would like some 17 x 8" wide wheels.
This actually has been discussed quite a lot, but it has been a while.

ou need two things to go to a wider tire: A wider wheel and a wider

ire that maintains an acceptable rolling diameter and doesn't run

nto things. Jim Bounds has wider wheels on the front of Larry, but

is source for those wheels was good luck, not anything that is really

epeatable. They can be custom-welded, but then you have heavy steel

heels. To go to a wider tire at the same rolling diameter, you need

ires with a lower profile that still have the weight rating, and when

e discussed this a year or two back nobody could identify the tires.

aybe they are available now, but I bet they aren't cheap.
I would not be a fan of going to 17" wheels. Frankly, I think a tall

idewall provides more compliance and absorbs more road texture. These

ow-profile tires look nice to the modern eye, but they are hard on

he fillings. And I'm sure I will offend someone by expressing the

pinion that a pickup truck with 22" wheels and a layer of what must

e solid rubber over them looks really silly.
Taller and narrower tires also provide better economy and better

raction in the wet with less likelihood of hydroplaning. Low profile

ires have more hysteresis in the sidewalls (unless you run them at

igher pressures) and make more heat when not being driven at the

imit of adhesion.
Those wide, low-profile tires sure are nice in tight corners, though.

hat isn't exactly the GMC's design envelope, however.
Rick "who enjoys paying a fraction of what the big RV owners pay for

ires" Denney
'73 230 Ex-Glacier "Jaws"

orthern Virginia
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[Ken Burton]

Rick Denney wrote on Mon, 23 November 2009 12&#58;42

> fluffyms writes...
>
> > Anyway, my question is - Going to a 16" wheel/tire, from a 16.5",
> > how will that effect the speedometer reading???
>
> The rolling diameter of one brand of 225/75R16 tires is 29.3", and
> they will all be similar.
>
> I tried to look up the rolling diameter of 8.75x16.5 tires, which were
> the original size on the GMC, and I can't find any online tire
> database that lists specifications for non-metric tires except for
> high-flotation mud tires. Thus, I suspect it has become impossible or
> nearly so to buy them. Your plan is a good one.
>
> Nominally, the 8.75 tire has a 78% profile, so the rolling diameter
> should be 30". That's 2.4% larger than the 225/75R16 tires--within
> normal error range of the speedo anyway. The 245/75R16 tires are about
> the same error in the other direction.
>
> Rick "who has seen both 225 and 245 tires on GMCs, but most go with
> 225" Denney
>
> '73 230 Ex-Glacier "Jaws"
> Northern Virginia

Rick,

I read somewhere that the revolutions per mile on the 8.75 16.5" tire was 719. The number for 225/75R16 is 710. If the 719 number is correct then the 16.5" tire we used was really slightly smaller in diameter than the 16" tires we are now using on the Alcoa and Eagle wheels.

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

[Rick Denney]

Ken Burton writes...

> I read somewhere that the revolutions per mile on the 8.75 16.5"
> tire was 719. The number for 225/75R16 is 710. If the 719 number
> is correct then the 16.5" tire we used was really slightly smaller
> in diameter than the 16" tires we are now using on the Alcoa and Eagle wheels.

I recall such numnbers, too, but I can't confirm them. One
manufacturer's tire specification reported 689 revoluations/mile for
their 225/75R16, with a rolling diameter of 29.3" (which is nearly
exactly the nominal size of a tire with a 225mm section, a 75%
profile, and a 16" wheel). The nominal rolling diameter of an 8.75"
tire (78% profile) is 30.15", with 669 revolutions per mile.

The revolutions per mile will always be a little higher because the
deformation of the tire decreases its rolling diameter slightly. But
the relative values should be the same.

For any given tire product, it could vary one way or the other by a
percentage point or two, I would think.

Rick "checkig his arithmetic" Denney

'73 230 Ex-Glacier "Jaws"
Northern Virginia

_______________________________________________

[D C *Mac* Macdonald]

Just for a bit of info whilst hoping my memory
hasn't gone away on this subject.

In the tire numbering system such as 225/75R16,
the 225 is the width in millimeters, the 75 is
the ratio (in percentage) of height of the tire
to its width, the R means radial construction,
and the 16 is the wheel diameter in inches.

Older numbering system had the first number in
inches, i.e., 6.70 x 15, etc. If the height/
width factor had been on those tires, it would
probably have been between 80 and 90, perhaps
even as much as 100 for truck tires.

In other words, the larger the second number,
the "taller" the tire is for any diameter and,
of course, vice versa. All other characteristics
being the same, the taller tires tend to give a
smoother ride and the shorter tires tend to give
more precise and stable handling.

D C "Mac" Macdonald
USAF, Retired
Ham Callsign - K2GKK
Oklahoma City, OK

[Jim Bounds]

If you are talking about tire diameter effect on your speedometer, let me throw in another wrinkle-- I am seeing a rather large range of differences in speedometer readings due to weak springs in the speedo head.  The years are taking it's toll on our hardware so having an "accurate" speedometer is pretty difficult to have.  You can tell you have a spring issue if you compare the speedo to a GPS readout at different speeds.  My reading has a 3 MPH difference at 40 MPH and a 10 MPH difference at 65 MPH.  Seems that the higher the speed the more off the speedo is.  Seems like that would not be a factor of a constant ratio rather the head itself.  Right now, the speedo simply fills the hole and gives me a relative speed when I do not connect up my GPS, for actual speeds I have to say the GPS does the trick so don;t go through a huge amount of expense and time trying to calibrate your 30+ ear old speedometer, it is probably going to change next month!

Jim Bounds
--------------------------

----- Original Message ----
From: Rick Denney <ri...@rickdenney.com>

[Roger P. Gleason]

You also need to keep in mind that GPS measures from hill top to hill top while the land speed will be different. This is an over dramatizaiton to make the point of how GPS works but it will be a factor in some areas as opposet to others.

[Charles Boyd]

rgleas wrote on Tue, 24 November 2009 09&#58;56

> You also need to keep in mind that GPS measures from hill top to hill top while the land speed will be different. This is an over dramatizaiton to make the point of how GPS works but it will be a factor in some areas as opposet to others.

So you are saying GPS is as "the crow flies"?? Maybe that is why it says the barn is one block down on the other side of the street.
--
C. Boyd
76 Crestmont by Midas
East Tennessee

[D C *Mac* Macdonald]

The coordinates, if shown, are probably quite accurate.
The problem lies in the accuracy of the mapping program.

D C "Mac" Macdonald
Oklahoma City, OK

----------------------------------------
> To: gmc...@temp.gmcnet.org
> From: covere...@comcast.net
> Date: Tue, 24 Nov 2009 09:17:47 -0600
> Subject: Re: [GMCnet] Tires
>
>
>
> rgleas wrote on Tue, 24 November 2009 09:56

[Ken Burton]

Rick Denney wrote on Tue, 24 November 2009 02&#58;19

> Ken Burton writes...
>
> > I read somewhere that the revolutions per mile on the 8.75 16.5"
> > tire was 719. The number for 225/75R16 is 710. If the 719 number
> > is correct then the 16.5" tire we used was really slightly smaller
> > in diameter than the 16" tires we are now using on the Alcoa and Eagle wheels.
>
> I recall such numnbers, too, but I can't confirm them. One
> manufacturer's tire specification reported 689 revoluations/mile for
> their 225/75R16, with a rolling diameter of 29.3" (which is nearly
> exactly the nominal size of a tire with a 225mm section, a 75%
> profile, and a 16" wheel). The nominal rolling diameter of an 8.75"
> tire (78% profile) is 30.15", with 669 revolutions per mile.
>
> The revolutions per mile will always be a little higher because the
> deformation of the tire decreases its rolling diameter slightly. But
> the relative values should be the same.
>
> For any given tire product, it could vary one way or the other by a
> percentage point or two, I would think.
>
> Rick "checkig his arithmetic" Denney
>
> '73 230 Ex-Glacier "Jaws"
> Northern Virginia

I got the 710 figure by looking up BF Goodrich Commercial TAs on Tire Rack's web site.

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

[Charles Boyd]

k2gkk wrote on Tue, 24 November 2009 10&#58;21

> The coordinates, if shown, are probably quite accurate.
> The problem lies in the accuracy of the mapping program.
>
> D C "Mac" Macdonald
> Oklahoma City, OK

Sir: I am not real "savy" on a lot of these new fangled thingies. I know that thanks to my wife and a good friend from downunder I have 2 GPS. One is a Commercial unit for big truck and one is a tourist type. They give different locations from the same place? Which is even different from Google or MSN.. Makes me think there might be a reason for me not knowing where I`m at most of the time??

[Rick Denney]

Charles Boyd writes...

> So you are saying GPS is as "the crow flies"?? Maybe that is why
> it says the barn is one block down on the other side of the street.

No, he's saying that GPS tracks speed in the horizontal plane only. If
the road is sloped, you'll be going a bit further than if it isn't.
But that is very slight and insignificant for our purposes. The
pavement distance on an 8% grade, for example, is only 0.32% greater
than the horizontal distance.

A bigger potential error is that GPS is measuring your speed by
measuring the distance over a period of time. That means that the
speed it reports is always lagging behind the true instantaneous speed
of the vehicle. Adding to that lag is the moving-average smoothing
that they do to filter out the effect of GPS location error. They
should be the same when traveling at a constant speed, though.

Rick "professionally curious about speed and travel time measurement"
Denney

'73 230 Ex-Glacier "Jaws"
Northern Virginia

_______________________________________________

[Rick Denney]

Ken Burton writes...

> I got the 710 figure by looking up BF Goodrich Commercial TAs on Tire Rack's web site.

Which tells me that the distribution describing 225/75R16 tires
overlaps the distribution describing 8.75R16.5 tires. Thus, the actual
difference between them will depend on the specific tires in question.
This confirms the conclusion that the error is small enough to ignore,
generally.

Rick "noting that all tire dimensions are 'nominal'" Denney

'73 230 Ex-Glacier "Jaws"
Northern Virginia

_______________________________________________

[Rick Denney]

Charles Boyd writes...

> Sir: I am not real "savy" on a lot of these new fangled thingies.
> I know that thanks to my wife and a good friend from downunder I
> have 2 GPS. One is a Commercial unit for big truck and one is a
> tourist type. They give different locations from the same place?
> Which is even different from Google or MSN.. Makes me think there
> might be a reason for me not knowing where I`m at most of the time??

They buy their map databases from different sources. What made all
this possible was going to county-wide addressing (which is called
different things in different places), and dispensing with the old
rural route addressing. This was done so that emergency responders
could use GPS-based navigation systems to respond to emergencies.

There are several companies that compile and sell map information to
the sat-nav industry. None of them are perfect and they are all a
little different. If you look at Google's road display on top of its
aerial photos, you'll see just how big (and strange) those errors can
be. They are still playing catchup in trying to correct all the errors
for roads that have been there forever, and then new roads are being
built all the time to keep them perpetually behind.

A newish consumer GPS getting a good signal will report your
horizontal location to the nearest 16 feet (WAAS standard accuracy).
But that doesn't mean it knows what else is around it to that same
accuracy.

My Garmin reports our address about 800 feet down the road from where
it actually is. And given our driveway puts us about 1000 feet back
from the road, we are about equidistant between two roads. Garmin
keeps trying to get me to drive across my backyard, through a
neighbor's woods, and then fording a creek to get to the other road.

Rick "whose eyes are more accurate than any map" Denney

'73 230 Ex-Glacier "Jaws"
Northern Virginia

_______________________________________________

[Charles Boyd]

.

My Garmin reports our address about 800 feet down the road from where
it actually is. And given our driveway puts us about 1000 feet back
from the road, we are about equidistant between two roads. Garmin
keeps trying to get me to drive across my backyard, through a
neighbor's woods, and then fording a creek to get to the other road.

Rick "whose eyes are more accurate than any map" Denney

'73 230 Ex-Glacier "Jaws"
Northern Virginia

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[/quote]

Thanks Rick "who don`t know where he is at either" Denny. That does splain a lot.

--
C. Boyd
76 Crestmont by Midas
East Tennessee

[D C *Mac* Macdonald]

Googlemaps will give you about the same accuracy!

D C "Mac" Macdonald
Oklahoma City,

USAF, Retired

----------------------------------------
> To: gmc...@temp.gmcnet.org
> From: covere...@comcast.net

> Date: Tue, 24 Nov 2009 12:00:34 -0600
> Subject: Re: [GMCnet] GPS Accuracy (was: Tires)

[Rick Denney]

D C *Mac* Macdonald writes...

> Older numbering system had the first number in
> inches, i.e., 6.70 x 15, etc. If the height/
> width factor had been on those tires, it would
> probably have been between 80 and 90, perhaps
> even as much as 100 for truck tires.

This is true, and normally we don't report the profile of the tires
with the old numbering system.

But the standard profile for passenger car and light truck tires
from that era was 78%. Knowing that, the other numbers are the same:
8.75" is the section width, 78% is the profile, and 16.5 is the
nominal bead diameter. I believe all these numbers are shown in
nominal form to allow one to calculate the rolling diameter from the
numbers, and the data I saw in that manufacturer's data sheet
reinforces that notion.

Off-road tires, on the other hand, are (still) reported by their
rolling diameter and width.

Emery: When I wrote that the rolling diameter changed with inflation,
there was a fingering wagging in the back of my brain. But I believe
it is possible to have a longitudinal slip, the same as a lateral
slip, as the tread squirms over the pavement. Maybe it takes airing
down way too far for it to be significiant. It's not really important
for this issue anyway.

Rick "remembering high school when his '70 Olds Cutlass wasn't cool
because it only had 'seventy-eights'" Denney

'73 230 Ex-Glacier "Jaws"
Northern Virginia

_______________________________________________

[Bob de Kruyff]

""It could have had something to do that the coach was built by the Truck &
Coach Division. I don't think GM provided much oversight on GM T & C.""

It wasn't so much an issue of oversight as it was familiarity with the component set that each group was familiar with. At that time, even the car divisions were separate and stand alone entities when it came to engineering and manufacturing.

--
Bob de Kruyff
78 Eleganza
Chandler, AZ

[Jay Rabe]

I'd heard that the GPS apps in cell phones are not "real" GPS. That is, they use triangulation from cell phone towers to determine your location, rather than receiving and triangulating from actual GPS satellite signals. As such, they are no good in the boondocks where there's no cell phone coverage.

Comments?

J

_________________________________________________________________
Hotmail: Trusted email with Microsoft's powerful SPAM protection.
http://clk.atdmt.com/GBL/go/177141664/direct/01/
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[Larry Davick]

Some cell phones have real GPS, but many do use towers to triangulate from. Some even use WiFi hotspots. Whatever gets you there.

My 1st gen iPhone has only the mock-gps for mapping and it's served me very well in a pinch.

Larry Davick
The Mystery Machine

----- Original Message -----
From: "Jay Rabe" <jay...@hotmail.com>
To: gmc...@temp.gmcnet.org
Sent: Tuesday, November 24, 2009 2:13:43 PM GMT -08:00 US/Canada Pacific
Subject: Re: [GMCnet] GPS Accuracy (was: Tires)

[Rick Denney]

Jay Rabe writes...

> I'd heard that the GPS apps in cell phones are not "real" GPS. That
> is, they use triangulation from cell phone towers to determine your
> location, rather than receiving and triangulating from actual GPS
> satellite signals. As such, they are no good in the boondocks where there's no cell phone coverage.

It depends on the cell phone. The iPhonoe 3GS has a real GPS in it.
But it starts with cell-tower triangulation as an initial location
method while waiting to acquire GPS satellites. The maps display shows
an accuracy circle that reveals the error of the current location
method.

Where being without cell coverage is debilitating is that it gets its
map information as needed from the 3GS data service, instead of
storing the map in the device as a Garmin does. I have apps for the
iPhone that allow me to download USGS topographic maps, and even
without cell coverage the phone will put me on those maps as long as I
have the map where I am stored in the phone.

Rick "who has tested the iPhone for these features" Denney

'73 230 Ex-Glacier "Jaws"
Northern Virginia

_______________________________________________

[Michael Lincoln]

Hi Rick,
What app permits the use of USGS maps?
Mike

Sent from my iPhone

[Jim White]

Rick-
I have 245/75R 16/E BFG All Season Tires. My tread width is 7.306 and
the revolutions per mile are shown as 680 vs. 707 for the 225/75R.

The best I can calculate is that the difference between the 245 and the
225 (both on 16" wheels) is that the speedometer would show the speed as
being about 4% slower than actual.

How can I determine the variation on the speedometer vs. the 16.5 inch
original sized tires? Is there a chart available.

Thanks-
Jim "Doc" (not Doctor) White
Wintergreen, VA
75 GMC Stretch (which likes it's new Eagles and BFG tires)
*******************

[Dan Gregg]

Jim, just use your gps, it is close. I never look at my speedometer but use the gps or the Scangauge, in the car. I have 245/75 tires on the coach, with a 355 final drive and a speedo correction unit. It is off about 5%, according to the gps. Good enough for me and the cops too.
Dan
--
Dan & Teri Gregg

danandteri.blogspot.com

///Halon Automatic Fire Extinguishers

[Jim White]

Dan-
Where did you get a speedo correction unit?
Doc

Dan Gregg wrote:
> Jim, just use your gps, it is close. I never look at my speedometer but use the gps or the Scangauge, in the car. I have 245/75 tires on the coach, with a 355 final drive and a speedo correction unit. It is off about 5%, according to the gps. Good enough for me and the cops too.
> Dan
>

[Dan Gregg]

Where I get everything, Jimmy K. :roll:

--
Dan & Teri Gregg

danandteri.blogspot.com

///Halon Automatic Fire Extinguishers

[Jim White]

Dan-
Is it dynamic or fixed? If I upgrade to a 3.70, do I have to get
another one?
Doc

Dan Gregg wrote:
> Where I get everything, Jimmy K. :roll:
>

[Matt Colie]

Almost no current cellphones actually contain a true GPS system. If it was, it would not work most of the time - just like even the newest of my stand-lone units. One of the things that never seems to get talked about (if you were installing car phones before cell) is the innovation that makes the cell technology work at all.

The system is comprised of cells (Duh). These cells are the area served by a single tower.
When a handset is moving (part of the original intent), the system has to know where it is so it can pass it off to the cell it is moving into. It can not do triangulation when an area is served by very few towers. It does this with a radial and bearing system. That is why cell towers have three antennas. That gets you the bearing and I have forgotten how they get radial distance. It is some sort of convoluted time in transit puzzle.

The some of the GPS handsets have the means to receive location information, but more often it is used in the central signal handling. Even those that are advertised as GPS handsets do not actually have usable location data onboard. I accosted a friend that has been an engineer with Motorola and On-Star when I was trying to hack into my T730c to retrieve the location data, he finally admitted that I could get it out of there because it isn't in there. Many On-Star units do have real GPS.

As to speed and travel distance accuracy, it is now much better than it was even 5 years ago. I have one old unit that will report velocity with a 0.1 resolution every second. It still is not accurate for distance traveled because the log is relatively low density - corners get cut. The most recent actually stores travel distance so well that I was able to use it to establish the error in the coaches odometer and straight or twisty road makes no difference.

I'll go back and sit down now.

Matt
--
Matt & Mary Colie
'73 Glacier 23 Chaumiere (say show-me-air)
SE Michigan

[Dan Gregg]

I dont know what dynamic or fixed means. I just use my gps. I don't even care if the speedo does not work except it runs my electronic cruise.
Dan

--
Dan & Teri Gregg

danandteri.blogspot.com

///Halon Automatic Fire Extinguishers

[Jim Bounds]

exactly!

Jim Bounds
--------------------------

[Jim Bounds]

Actually the next coach in production will probably use the face of the speedo as a recessed location for the GPS unit.  it will only be used if the GPS goes out.  Hey, it's the sign of the times!

Jim Bounds
-----------------------

----- Original Message ----
From: Dan Gregg <greg...@hotmail.com>
To: gmc...@temp.gmcnet.org
Sent: Tue, November 24, 2009 9:25:16 PM
Subject: Re: [GMCnet] Tires

[Larry]

--
Larry :)
78 Royale w/500 Caddy
Menomonie, WI.

[Larry]

FWIW, Here is what I did when I found my speedo reading 7mph slower that I was actually going.
http://www.gmcmhphotos.com/photos/showgallery.php?cat=3470

This little speedo cost me about $20.00 at the local bike shop, and when set up properly is accurate to 99mph. It reads right on with my GPS.
Just what I did....

[Rob Mueller]

Larry,

Boy, you sure must have some fast bike riders in Menomonie! ;-)

I noticed the tach has a red line at 3000. Why?

Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426

[Dan Gregg]

Hey Larry, I like it. Can you buy these in most bike shops for 20 bux?

Dan
--
Dan & Teri Gregg

danandteri.blogspot.com

///Halon Automatic Fire Extinguishers

[Rick Denney]

Michael Lincoln writes...

> Hi Rick,
> What app permits the use of USGS maps?

It's called "Topo Maps", by Philip Endicott. He provides an overall
map showing the boundaries of 7-1/2' quads, and when you touch them,
you download the maps. The maps themselves are direct scans of USGS
maps, warts and all, but located in the GIS accurately. You can even
cross map boundaries almost seamlessly, which is the first time I've
seen that feature in a USGS map application for any computer. You must
download the relevant maps while you have a good 3G or (preferably) a
WiFi connection. But once downloaded, they are stored on the device
permanently--not in a volatile cache as with some other programs.

I've used it for long hikes in the Appalachian Mountains where cell
service is spotty at best. The only downside is the GPS hammers the
iPhone battery.

There is another app which is a neat one for GMC owners, and it is
called "Traffic!" from Inrix. Inrix is a major player in the provision
of travel time and traffic flow information in the biz, and this app
will drop you on a Google map, and also show (by color-coding) the
speed of traffic on major routes. It gets the information from cell
phone users by triangulation from the infrastructure side--even those
users who don't know they are contributing (anonymously, of course) to
that data. You have to agree to be part of that data source by using
the app.

Still another GMC-useful app is called "Park Maps", which provides the
standard Park Service brochure map for all facilities run by the
National Park Service, or so they claim. I've only looked at a couple
of those maps so far, but those maps often showed just the important
stuff for a lot of people.

I won't even get into the SPL meter, the real-time audio analyzer, and
the audio spectrum analyzer, with which we could settle once and for
all who has the quietest coach.

Rick "and then there's the weather radar..." Denney

[Rick Denney]

Jim White writes...

> Rick-
> I have 245/75R 16/E BFG All Season Tires. My tread width is 7.306 and
> the revolutions per mile are shown as 680 vs. 707 for the 225/75R.

Jim, the 245 is the section width, not the tread width. That's the
widest part of the tire. The nominal rolling diameter of 245/75R16
tires is 30.47 inches, which should be 662 revolutions per mile. That
doesn't mean that's what yours are, that's just the nominal value. We
can't determine what tires really are, but we can compare different
sizes using those nominal values.

The nominal diameter of a 225/75R16 is 29.3 inches or 689 revolutions
per mile. The difference in diameter is 75% of double the difference
in section. So, the difference in section is 20mm, and twice that is
40mm. 75% of that is 30mm, which is about 1.2". That's about 4%. The
change in speedometer reading should be exactly that, because the
diameter and the circumference (or revolutions per mile, which is
another way to describe the circumfernce) are related by a constant
(pi).

The 8.75 tires are in between those two sizes.

> The best I can calculate is that the difference between the 245 and the
> 225 (both on 16" wheels) is that the speedometer would show the speed as
> being about 4% slower than actual.

Yes, assuming "actual" is really "actual". My speedometer read
significantly low with a 3.07 final drive and stock 8.75" tires on
stock rims. When it read 70, I was really going about 76 (heh, heh).
That's as reported by GPS at constant speed on flat terrain, over a
period of time.

Going to 225s probably made it a little worse.

> How can I determine the variation on the speedometer vs. the 16.5 inch
> original sized tires? Is there a chart available.

I tried to find a manufacturer's data sheet for an 8.75" tire, but
since none list those tires sizes on their websites any longer, I
couldn't find one. Going with nominal values, however, the diameter
should be 30.15", and I think if you compare nominal-to-nominal,
you'll be close enough. So, the 225's will read 2.9% fast, and the
245's will read 1.1% slow, compared to OEM. I must reiterate, however,
that we can't assume the OEM speedos are accurate. GM just didn't try
to make them more accurate than about 5-10%, it seems to me. Like I
said before, I had a '74 GMC pickup with OEM everything that read
nearly 10% high even when only four years old. My '84 Ford pickup,
bought new, read significantly high until I put oversize tires on it.
I think those speedos were calibrated for the tires we young urban
cowboys wanted, not what they came with.

Or, maybe GMC was hoping to contribute to local governments.

Rick "Officer, my speedometer MUST be wrong!" Denney

[Larry]

WD0AFQ wrote on Wed, 25 November 2009 08&#58;08

> Hey Larry, I like it. Can you buy these in most bike shops for 20 bux?
> Dan

Hey Dan,

Well, they were $20 five years ago when I did that project. Might even find them cheaper at Walmart. You must read the directions carefully to program the mini computer in it. I chalk marked a tire and a spot on the road. Ran it forward i turn, and measured the distance. Used that figure in the calculations to determine how to program the speedo. The first time I did it, I was going 60mph in reverse by the time I hit the end of my 60ft driveway...LOL....so be fussy about reading the directions. Then keep the directions and notes on how to do it in your glove compartment, because you will need them every 2-3 yrs when you replace the battery. JWID

--
Larry :)
78 Royale w/500 Caddy
Menomonie, WI.

[Rick Denney]

Two folks have sent me emails privately with information. One reminded
me of a post Emery Stora made several years ago, referencing a
Goodyear datasheet that was available then but not now. Those two
messages described the diameter (which is not the same thing as the
rolling diameter) as 28.9, 29.3, and 30.7", respectively, for 8.75,
225, and 245 tires.

It is interesting to note that the 8.75" Goodyear tire had a smaller
rolling diameter than the 225 tire, and much smaller than its nominal
size rating. The 245 tire was significantly larger than its nominal
size (by a quarter inch in diameter), while the 225 was right on its
nominal size. So much for my hope of making reasonable comparisons
based on nominal sizes. That tells me that any discussion of these
will vary by tire manufacturer to the point where the differences
between the OEM and the 225 are really clouded, unless one considers
specific tires. In that case, a tape measure might be the preferred
tool for evaluating the difference, as long as the tires are inflated
to the same pressure and loaded the same way.

If we go with Goodyear's revolutions per mile specification from the
data I was sent (which is based on rolling diameter and not ono the
diameters reported above), we have:

8.75: 719
225: 703
245: 671

With that, the speedo will read 2.2% slower for the 225 tire than the
8.75" tire, and the 245 will be nearly 5% slower than the 225. If I
put 245's on my coach, maybe the speedo would be almost accurate, heh,
heh.

I used 225's because I didn't see much value in a larger tire--we
don't need the extra load handling, nor do we want a taller gear
ratio.

Rick "thinking it's time for 16.5" users to start saving up" Denney

[Matt Colie]

WD0AFQ wrote on Wed, 25 November 2009 09&#58;08

> Hey Larry, I like it. Can you buy these in most bike shops for 20 bux?
> Dan

Dan,
If you don't score there, try E-bay. I think I do two for less than that.

Matt
--
Matt & Mary Colie
'73 Glacier 23 Chaumiere (say show-me-air)
SE Michigan

[Matt Colie]

Larry,

Question - Why did you pick the left side?

I am planning to use the right when I do a similar thing. I am going to install a Prefect Circle/Dana cruise (I'm tired of the GMC unit).

This is the cruise that was later became Rostra, but these are still analog. I have two almost complete kits.

This, Hadley air horns (no budget for Airchimes) and a few other things out of my parts bins that are left over from old projects.

Matt
--
Matt & Mary Colie
'73 Glacier 23 Chaumiere (say show-me-air)
SE Michigan

[Dan Gregg]

Larry, this is hard to believe. That thing will actually program to work on a vehicle? They are selling anywhere from a dollar to 20 on ebay. How in the world can that work? I am assuming that they program from the head unit somehow based on the diameter of what you mount the sensor on? Did you have to add wire to your's to make it long enough to reach your dash? You are just too inovative.

Dan
--
Dan & Teri Gregg

danandteri.blogspot.com

///Halon Automatic Fire Extinguishers

[Rick Denney]

Dan Gregg writes...

> Larry, this is hard to believe. That thing will actually program to
> work on a vehicle? They are selling anywhere from a dollar to 20 on
> ebay. How in the world can that work? I am assuming that they
> program from the head unit somehow based on the diameter of what you
> mount the sensor on?

I rememeber when Larry did this--it was one of the first truly
hilarious and brilliant GMC tricks I saw. There have been many since
then.

The bicycle speedometer uses a magnet moving past a reed switch or
hall-effect sensor. They can be calibrated by identifying (usually in
centimeters) the diameter of the wheel. They provide speed and trip
statistics. Some even have a wireless connection between the sensor
and the head, if you don't mind changing batteries from time to time.
The magnets are usually installed on a spoke and the sensor on the
fork blade, but that's just because that's what is available on a
bicycle.

The diameter of a typical tire on a racing bicycle is a little over 28
inches--within two inches of a GMC tire. They just have more wheel and
less tire.

And they will read high speeds with no trouble. I've read 50 mph on my
bicycle speedometer--on a bicycle.

Rick "who occasionally now looks at those bikes when walking past them
in the basement" Denney

'73 230 Ex-Glacier "Jaws"
Northern Virginia

_______________________________________________

[Gary Casey]

But....the same lateral compliance that reduces the loading during low speed tight turns also reduces the stability at high speed.  Pays your money and takes your choice, I guess.  I have Alco wheels on the front and steel wheels on the back, so I have the painful decision ahead (since my rear tires are nearing their end) of buying new wheels or just replacing the rears with (taller?)16.5's.  Painful.
Gary

My thoughts are that the taller sidewall is beneficial on the rear of the GMC, especially a 23 ft, as the relatively short wheelbase with the tandem wheel set-up puts a lot of side force on the tires when "parking lot" turning. If you want a visual, start a sharp turn when parking and while the front wheels are still are max stop the coach, get out and look at the distortion on the rear tires/wheels.

Dennis

Dennis Sexton
73 GMC
Germantown, TN
USA

Don Adams writes...
> I also wonder why no one mentions going to a wider wheel,
availability I guess.  Jim K mentioned one time he was looking at
17" wheels.  Your favorite BFG TA's are available in 17" diameter.
Sure would like some 17 x 8" wide wheels.
This actually has been discussed quite a lot, but it has been a while.
ou need two things to go to a wider tire: A wider wheel and a wider
ire that maintains an acceptable rolling diameter and doesn't run
nto things. Jim Bounds has wider wheels on the front of Larry, but
is source for those wheels was good luck, not anything that is really
epeatable. They can be custom-welded, but then you have heavy steel
heels. To go to a wider tire at the same rolling diameter, you need
ires with a lower profile that still have the weight rating, and when
e discussed this a year or two back nobody could identify the tires.
aybe they are available now, but I bet they aren't cheap.
I would not be a fan of going to 17" wheels. Frankly, I think a tall
idewall provides more compliance and absorbs more road texture. These
ow-profile tires look nice to the modern eye, but they are hard on
he fillings. And I'm sure I will offend someone by expressing the
pinion that a pickup truck with 22" wheels and a layer of what must
e solid rubber over them looks really silly.
Taller and narrower tires also provide better economy and better
raction in the wet with less likelihood of hydroplaning. Low profile
ires have more hysteresis in the sidewalls (unless you run them at
igher pressures) and make more heat when not being driven at the
imit of adhesion.
Those wide, low-profile tires sure are nice in tight corners, though.
hat isn't exactly the GMC's design envelope, however.
Rick "who enjoys paying a fraction of what the big RV owners pay for
ires" Denney
'73 230 Ex-Glacier "Jaws"

[Larry]

WD0AFQ wrote on Wed, 25 November 2009 16&#58;14

> Larry, this is hard to believe. That thing will actually program to work on a vehicle? They are selling anywhere from a dollar to 20 on ebay. How in the world can that work? I am assuming that they program from the head unit somehow based on the diameter of what you mount the sensor on? Did you have to add wire to your's to make it long enough to reach your dash? You are just too inovative.
> Dan

Dan,
Rick is right in his description of how it works. I was riding my bike on a trail one morning thinking about what I was going to do with a coach speedo that read 55 when I was actually doing 62. (my wife drove the towd next to me on a 4 lane road with walkie talkie) It just came to me as I was looking at the bike speedo on my bike. I had just installed it on my bike a few weeks before. Tire is about the same diameter as GMC tire, and the speedo can be programed to work on kids bikes on up to racers. Stood to reason that it could work on a vehicle...*IF* it read above 30 or 40 mph.

The head unit is programed based on tire diameter...axle is connected to tire and obviously turns at same rate as tire, so I put sensor on the axle. Then had to add wire so that it would reach the dash. That was the hardest part...the wires are very, very, very fine. Anyway, it works. Down side is that it is not back-lit, so you cannot read it at night, batteries have to be changed every 2 yrs or so requiring a reprograming, and it doesn't read over 99mph...a recurring problem ;)

--
Larry :)
78 Royale w/500 Caddy
Menomonie, WI.

[Jeff Willard]

Not necessarily revelant here... but a factoid none the less.
My Prince On-board Trip computer has a speed sensor in-line with the speedo cable and needs to be "Calibrated". The standard starting value is 800 and on my Alcoa'd coach ran fast. I adjusted it to 835 and it's about as close as I can get. I don't know the ratios for speedometer gearing, and the final drive gear would also factor in.

We now return to our regularly scheduled programming....
--
Jeff Willard
Silver City, NM
1973 ex-Glacier

[Steven Ferguson]

Heh, heh. Love that cabin bound dry humor.

--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/

[Richard B Cortezzo]

Now that I have gotten my Eagle center hubs rims from Jim,
what brand of tires have you guys had any luck with?

Jim says to stay away from steel belts in the sidewalls.
Any input will help me a lot.

Rich Cortezzo
1978 Eleganza II
--
Rich Cortezzo
Green Valley AZ
1978 Eleganza II

[George Groth]

Rich, I'm running BFG ragwall from Costco. Not that many miles on them but they are holding up well.
--
geo groth '73 260 Sequoia
Carson City Nevada

[Rob Mueller]

Rich,

I followed Ken Burton's lead and got Khumo Road Venture KL78 tires for
Double Trouble in the USA. I have put around 7000 miles on them in the past
two years with no problems. I use Equal balancing beads in the tires.

http://tinyurl.com/y8ogq3e

http://www.kumhousa.com/Tire.aspx?id=8ce40218-bc5c-47d0-ac9c-3207a8c1c3a3&ca
t=25

I got them from the Tire Rack.

Regards,

Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426

[Ken Burton]

That question will give you as many answers there are tire brands.

IF you want to spend a lot of money then buy Michelin.

A lot of people buy BF Goodrich from Sam's or Costco.

If you want more traction on dirt and grass then go with the Kuhmo Road Venture AT. Mine were less than $100 each. I have them and so does Rob Mueller. The off pavement traction is excellant.

So there you have three choices. Next people will add Goodyeat, Cooper, Bridgestone, and a couple of Chinese brands.

I would not worry about tread life. Most people throw the tires away after 5 to 10 years due to age not because they are worn out.

Good luck making a decision.

Ken B.

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

[Dan Gregg]

Rich,
BFGoodrich Commercial TA E range will give you good service at a reasonable price. They are the ragwalls that you want. Sam's Club and others carry them. You are close to Steve F. Give him a call. He will give you a good straight answer on tires.
Dan
Heading your way soon

--
Dan & Teri Gregg

danandteri.blogspot.com

///Halon Automatic Fire Extinguishers

[Rick Denney]

Richard B Cortezzo writes...

> Jim says to stay away from steel belts in the sidewalls.

What you want to avoid are "all-steel" tires. All tires have steel
belts nowadays. You don't want a steel fabric cord.

I have had good luck with cheapie tires found by my local tire guy,
and others have had good luck with Kumho tires. Still others like the
BF Goodrich Commercial T/A tires. I have a bias against Firestone but
I'm not too much concerned beyond that, as long as the tires are
steel-belted, polyester sidewall construction and not all-steel.

Rick "thinking inflation is also important" Denney

'73 230 Ex-Glacier "Jaws"
Northern Virginia

[Richard B Cortezzo]

I bought the kuhmo tires at tire rack 80 dollars a tire.

Rich Cortezzo

[Rob Mueller]

Rich,

I sure hope you didn't buy:

225/75R16
Load Index 104 = 1984lbs (900kg) per tire
Speed Rating "S" = 112mph (180kph)

If you check your Operating manual you will find that the front GAWR is
4,200 lb. Two of the tires above are rated at 3968 lb.

The Khumo's I have are:

225/75R16
Load Index 115 = 2721lbs (1237kg) per tire
Load Index 112 = 2484lbs (1129kg) per tire
Speed Rating "Q" = 99mph (160kph)

They cost $100 each.

Reference:

http://tinyurl.com/ygqnwh9

http://www.tirerack.com/tires/Sizes.jsp?make=Kumho&model=Road+Venture+AT+KL7
8

Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426

-----Original Message-----
From: gmclist...@temp.gmcnet.org
[mailto:gmclist...@temp.gmcnet.org] On Behalf Of Richard B Cortezzo
Sent: Thursday, 3 December 2009 10:48 AM
To: gmc...@temp.gmcnet.org
Subject: Re: [GMCnet] Tires

[Marcel Bourgon]

Good afternoon from Snowy El Paso.
Would like to do something with my two benches and folding table. Probably
two chairs and folding table. How about some ideas.
thanks
Marcel in El Paso

----- Original Message -----
From: "Rob Mueller" <robmu...@iinet.net.au>
To: <gmc...@temp.gmcnet.org>
Sent: Wednesday, December 02, 2009 5:15 PM
Subject: Re: [GMCnet] Tires

[Ken Henderson]

Marcel,

Apparently you selected REPLY to Rob's message about tires. THAT's how
thread are broken and polluted. If you're changing the subject, it's
essential that you start a fresh message, NOT REPLY.

Broken threads don't mean much to those of us who use the original email
GMCNet, but those who participate through the Forum lose track of the
conversation.

We have to have this conversation from time to time to keep everyone
educated.

Ken H.

On Wed, Dec 2, 2009 at 8:16 PM, Marcel Bourgon <mjbo...@earthlink.net>wrote:

> Good afternoon from Snowy El Paso.
> Would like to do something with my two benches and folding table. Probably
> two chairs and folding table. How about some ideas.
> thanks
> Marcel in El Paso
> ----- Original Message -----
> From: "Rob Mueller" <robmu...@iinet.net.au>
> To: <gmc...@temp.gmcnet.org>
> Sent: Wednesday, December 02, 2009 5:15 PM
> Subject: Re: [GMCnet] Tires
>
>
>

[Chris Choffat]

GMCWiperMan wrote on Wed, 02 December 2009 18&#58;23

I second that. Doing that kills the sequence of the conversation and makes it frustrating to follow, so much that when a thread is split, I quit.
--
-Chr$: Perpetual SmartAss
77 Ex-Kingsley 455: The Engineer's Motorhome
Scottsdale, AZ

[Mr.erf ERFisher]

> * so much that when a thread is split, I quit.*
>

lets don't start this again,

Since there are no rules, When this happens, just start a new thread, with
the correct title.

It is always good to start fresh, and get rid of the previous 435 posts ;>)
I prefer more threads, than longer threads.

gene

--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html

[Jim Bounds]

Were those "E" rated?  Man, that is an unbelievable price compared to Bridgestone & Michelins being over $200 each!  I am also using the offshore times, they work well in our application.

Jim Bounds
--------------------------

----- Original Message ----
From: Richard B Cortezzo <rscor...@yahoo.com>
To: gmc...@temp.gmcnet.org
Sent: Wed, December 2, 2009 6:47:42 PM
Subject: Re: [GMCnet] Tires

[Rob Mueller]

Jim,

I sent the following message:

Rich,

They cost $100 each.

Reference:

http://tinyurl.com/ygqnwh9

http://www.tirerack.com/tires/Sizes.jsp?make=Kumho&model=Road+Venture+AT+KL7
8

[Gary Casey]

I just saw BJG's on closeout at Tire Rack for something like $68. I'm not in the position to buy them at the moment, but someone might.
Gary

________________________________
From: Jim Bounds <gmc...@yahoo.com>
To: gmc...@temp.gmcnet.org
Sent: Thu, December 3, 2009 5:54:19 AM
Subject: Re: [GMCnet] Tires

[Randy]

When you buy tires off the internet, do you pay tax and what is the average installation price?

Are fresh tires that are cheaper better for coaches that don't get alot of miles, or are the cheaper tires a risk not worth taking? In short are you better off with a set of Hirohito 1000's that you change every 4-5 years than a set of Michelins that you try to stretch to 8-9 years?

--
Randy
1973 26' Painted Desert
Ahwatukee (Phoenix) AZ

[Kosier]

Randy,

If you try to stretch those Michelins for 8-9 years, be prepared
to do some damage repair.
I lost three at six years and the last one was one the spare tire
rack. Never again!

Gary Kosier
77EII & 77PB
Newark, Ohio

----- Original Message -----
From: "Randy" <Acros...@hotmail.com>
To: <gmc...@temp.gmcnet.org>
Sent: Thursday, December 03, 2009 10:13 PM
Subject: Re: [GMCnet] Tires

>
>

[Rob Mueller]

Randy,

My Kuhmo's were mounted by Ken Frey when we were getting it ready last year.
I can't remember what he charged me to mount and toss four ounces of Equal
into each tire. I'd say to get tires you get off the internet mounted you
would have to go to a local garage that didn't sell tires for a living and I
think I'd find a shop that would mount them BEFORE I bought them!

When I bought Double Trouble it had a set of steel sidewall Goodyear G159's
on it that were over 7 years old. They had heaps of thread and the sidewalls
looked like new. I hemmed and hawed and finally Steve Ferguson hit the nail
on the head when he said; "the Goodyear 159's will probably be fine BUT
you're going to worry for the whole trip that one might let go." I realized
that he was right so replaced them.

When the Kuhmo's arrived I was surprised to discover that they were made in
CHINA as Kuhmo is a Korean company.

Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426

-----Original Message-----
From: gmclist...@temp.gmcnet.org
[mailto:gmclist...@temp.gmcnet.org] On Behalf Of Randy
Sent: Friday, 4 December 2009 2:13 PM
To: gmc...@temp.gmcnet.org
Subject: Re: [GMCnet] Tires

[Ken Burton]

Robert Mueller wrote on Thu, 03 December 2009 23&#58;07

If you go on their web site you can enter your location and they will give you installers in your area. I have also found that most, if not all, Wal-marts will mount and balance them for $10.00. each. They also include a new valve but I do not know if they have the correct valves for Eagles or Alcoas so you probably should bring your own. I have Equal in mine instead of having them balanced. They did not care about the Equal I supplied. They just throw in the bag but be sure to tell them no weights.

If you are in the area of South Bend, Tire Rack will also mount and balance them at their store. I had two done on my Colorado truck on the way to the GMC Eastern States rally this fall.

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

[David L Greenberg]

On Thu, 03 Dec 2009 21:13:26 -0600 Randy <Acros...@hotmail.com> writes:
>
>
> When you buy tires off the internet, do you pay tax and what is the
> average installation price?
>

No tax (if the seller is not a corporate entity in your state)-no
disposal fee but you do pay transport fees which are close to state tax)

> Are fresh tires that are cheaper better for coaches that don't get
> alot of miles, or are the cheaper tires a risk not worth taking? In
> short are you better off with a set of Hirohito 1000's that you
> change every 4-5 years than a set of Michelins that you try to
> stretch to 8-9 years?
>

Randy, I always bought the best affordable tires and replaced them at 5
years if they didn't wear out before that.

In my opinion tires are a safety item that I wouldn't skimp on. Do your
research and you'll find a good price for a good tire. The last set I
bought were Cooper SMR IIs designed for RV use, paying $100 apiece. I had
good wear and not a single problem in 40k miles. They replaced the
Bridgestones I had been using for years but had gotten too expensive.

I put Kumhos on the ASC McLaren I had to replace the 18 years old OEM
issue and was very impressed with them but didn't keep the car very long
afterward. I might consider a Korean tire but would look at user reviews
1st before I bought anything.

David Lee Greenberg
Port St Lucie, FL
Dedicated to the Preservation of the Classic GMC Motorhome
http://GMCmhRegistry.com
48 Packard Super Eight http://www.picturetrail.com/gmcregistry
____________________________________________________________
Weight Loss Program
Best Weight Loss Program - Click Here!
http://thirdpartyoffers.juno.com/TGL2141/c?cp=LZeIxVikpZuiTviQzlCAQAAAJ1Csyv5OnZl2mKFYY98JLnqKAAYAAAAAAAAAAAAAAAAAAADNAAAAAAAAAAAAAAAAAAAEUgAAAAA=

[Richard B Cortezzo]

Robert

Thanks for the heads up. I did get the wrong tires,
but was able to get the correct tires. Tire Rack seems
like a good place to shop for tires. Great service and
they won't sell the wrong tires.

Rich Cortezzo
1978 Eleganza II

--

[Rob Mueller]

Richard,

All well that ends well! Thanks for confirming that you got the right ones
in the end.

When I bought The Blue Streak it had BRAND NEW tires on it and I was really
pleased with that, however, I didn't examine them closely until I got it to
my workshop when I noticed that they were SUV tires NOT light truck tires.
They were WAY under rated for a GMC! I got lucky and sold them for a
reasonable price and got E rated tires!

Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426

-----Original Message-----
From: gmclist...@temp.gmcnet.org
[mailto:gmclist...@temp.gmcnet.org] On Behalf Of Richard B Cortezzo
Sent: Friday, 4 December 2009 11:20 PM
To: gmc...@temp.gmcnet.org
Subject: Re: [GMCnet] Tires

Robert

Thanks for the heads up. I did get the wrong tires,
but was able to get the correct tires. Tire Rack seems
like a good place to shop for tires. Great service and
they won't sell the wrong tires.

Rich Cortezzo
1978 Eleganza II

_______________________________________________

[Gary Casey]

Just to fill me in, I thought the "D" rated tires were rated for something like 65 psi and the "E" tires were 80 psi. Correct? If so, as I recall the actual load rating is dependent on the actual pressure used, so the E rated tire when run at 60 psi is rated at the same load as a D tire at 60. I remember talking to a tire guy that said the lower rated tire is actually slightly better because it won't run as hot as the higher rated tire. But that might be back in the days where they added load rating by adding plies. So the question is why get an E rated tire if you're not going to run it at any more pressure than the D rated tire?
Gary, about to buy tires.

________________________________

From: Richard B Cortezzo <rscor...@yahoo.com>
To: gmc...@temp.gmcnet.org

Sent: Fri, December 4, 2009 5:20:16 AM
Subject: Re: [GMCnet] Tires

Robert

[Rob Mueller]

Gary,

You're correct vis-à-vis the max pressure ratings of the D and E tires. I
think you're also correct vis-à-vis the pressure and the amount of load the
tires can carry for the D and E tires at 60 psi.

Once again I followed Ken Burton's lead and I run 65 psi in the fronts and
60 in the backs. I bought the E rated Kuhmo tires as that way I wouldn't be
running at the max pressure on the fronts.

Whether that's right or wrong; smart or stupid I'm happy with the way the
Kuhmos perform and the E rated tires were only $5.00 more than the D rated.

Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426

-----Original Message-----
From: gmclist...@temp.gmcnet.org
[mailto:gmclist...@temp.gmcnet.org] On Behalf Of Gary Casey
Sent: Friday, 4 December 2009 11:54 PM
To: gmc...@temp.gmcnet.org
Subject: Re: [GMCnet] Tires

[Charles]

Rob,
You posted:

The Khumo's I have are:
225/75R16
Load Index 115 = 2721lbs (1237kg) per tire
Load Index 112 = 2484lbs (1129kg) per tire
Speed Rating "Q" = 99mph (160kph)
They cost $100 each

Where and when did you get these for $100.00.
The cheapest I have found them is $128.00 at Discount tire.
After mount, Balance, Road Hazard they are $156.27
Discount will match your price if I can still find them at you price.
The import tax out government put on foreign tires is killing me.
http://www.discounttire.com/dtcs/findTireDetail.do?tc=KUMVL4&c=1&rcz=75116&pc=33637&ar=75&rf=false&cf=false&rd=16&sw=false&rc=TDSINT&cs=225
Charles

[Rob Mueller]

Charles,

The $100 is the current price on the Tire Rack.

Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426

-----Original Message-----
From: gmclist...@temp.gmcnet.org
[mailto:gmclist...@temp.gmcnet.org] On Behalf Of Charles
Sent: Saturday, 5 December 2009 12:34 AM
To: gmc...@temp.gmcnet.org
Subject: Re: [GMCnet] Tires

[Jim Bounds]

Something I did so far only once but in trying to help those that were wanting to get accuratly trued and balanced new 16" rims and tires-- I picked up the Nexen tires here, Jim K. sent me the set of Eagle rims, I loaded the tires actually on a coach, warmed them up then trued and balanced them and shipped them to the customer laced up and ready to go.  The shipping had to go truck freight which added to the total cost a bit but the whole rim/tire assembly was in perfect balance and trued.  It was a bit of a hassle, probably not worth all it took to do it for me but it did offer truing and balancing to a guy that just could not drive down here to get it done.

If you would really like to get a jam up set of sneakers for your coach, this is a way to  do it.  The $ you save in the rims and the tires gives you the opportunity to have the new 16" set up still cheaper than buying Alcoa rims with Michelin tires without the benifit of what I feel is the best way to set up tires and rims. 

Just a thought for those who care, call me if you are interested,

Jim Bounds
------------------------------

----- Original Message ----
From: Rob Mueller <robmu...@iinet.net.au>
To: gmc...@temp.gmcnet.org
Sent: Fri, December 4, 2009 7:46:28 AM
Subject: Re: [GMCnet] Tires

[Steven Ferguson]

Randy,
After all is said and done, cussed and discussed, the bottom line is
for you to find a load rated E tire of the correct size and
construction, inflate them to the Mfr's specs, keep them covered when
not in use, and replace them when worn, or at the 5-6 year mark.
Anything other than that and you will have your decision on your mind
everytime you and yours are out for an outing.

--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/

[John Wright]

Randy,
I have to agree with Steve when it comes to purchasing tires for the
coach. I am not trying to start a "TIRE WAR!" here on the GMC net
which we have done several times the past few years. On the 77 coach
I run the BFG Commercial T/A (225 75R 16 LRE) tire on all wheels and
they ride great and are bead balanced. These are a all ragwall tire
and are 65# in all tires. The 75 coaches tires are Goodyear G149 (225
75R 16 LRE) all steel tires on the rear set at 60# and Goodyear
Wrangler HT's (225 75R 16 LRE) set at 65# and they are a ragwall
tire. You will notice that the fronts on both coach are a ragwall
tire. General consensus although not agreed by all is that the
ragwall tire will improve your drive and ride down the road. I have
driven with all steel tires, all ragwall tires and steel on the back
and ragwall on the front. The all steel was the worst ride of the
three.

As for tire pressures you will hear all different ranges used by
GMCers. Some swear by running the manufactures rating on the tires
and on the LRE tire that most always is 80 PSIG and it rides like a
truck. You can also have the coach weighed and set the pressure by
the weight or you can run what someone else runs. I have run as low
as 55# on the old Goodyear G159 in the past but today I run 60 or 65#
on the rear depending on the tire and 65# on the front and that is my
personal choice and yours may vary.

As for how long to run the tire, the run of thumb today is 5 to 7
years depending on tire make. I had a fellow GMCer who also worked
for Goodyear tire say that you could run the old G159 for 10 years
with problems because of the additives that they used in the rubber
and some who run Michelins for 7 or 8 years for the same reason.
Today the tire companies do not use the same formulation of rubber
that they used in the past that protects the rubber (primarily UV
protection). And what is really scary is the number of Brand Name
tires that you would think that are US made are really made in China.
My tire supplier told me this when I bought a set of tires for the
tracker. That is why the 30% tariff on tires has raise almost all
tire prices.

Not going to tell you which tire range and brand you should buy. Go
out there and make your best deal. Just remember that the cost to fix
body and running gear damage is considerably more that the small
difference between D & E rating cost.

I will get off my soap box now.

J.R. Wright
GMC GreatLaker
TZE Zone Restorations
77 Eleganza Custom (For Sale)
1975 Avion (Under Reconstruction)
Michigan

> Randy,
> After all is said and done, cussed and discussed, the bottom line is
> for you to find a load rated E tire of the correct size and
> construction, inflate them to the Mfr's specs, keep them covered when
> not in use, and replace them when worn, or at the 5-6 year mark.
> Anything other than that and you will have your decision on your mind
> everytime you and yours are out for an outing.
>

[Rob Mueller]

Jim,

BTW a mate of mine is the importer of Nexen tires here in Australia, guess
what kind of sneakers are on The Blue Streak!

Jim Bounds
------------------------------

_______________________________________________

[Peter Bailey]

Rob,
You know there is no 'i' in the word tyres
Peter Bailey

----- Original Message -----
From: "Rob Mueller" <robmu...@iinet.net.au>
To: <gmc...@temp.gmcnet.org>
Sent: Saturday, December 05, 2009 8:51 AM
Subject: Re: [GMCnet] Tires

[Ken Burton]

Charles wrote on Fri, 04 December 2009 07&#58;34

> Rob,
> You posted:
> The Khumo's I have are:
> 225/75R16
> Load Index 115 = 2721lbs (1237kg) per tire
> Load Index 112 = 2484lbs (1129kg) per tire
> Speed Rating "Q" = 99mph (160kph)
> They cost $100 each
>
> Where and when did you get these for $100.00.
> The cheapest I have found them is $128.00 at Discount tire.
> After mount, Balance, Road Hazard they are $156.27
> Discount will match your price if I can still find them at you price.

http://www.tirerack.com/tires/TireSearchResults.jsp?skipOver=true&width=225%2F&ratio=75&diameter=16&x=19&y=5

Choose the KL78's

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

[Rob Mueller]

Ken,

I'd love to see the Load Range D and Load Range E side by side to compare
all the info on the side walls. I really wonder if there is REALLY any
difference between them. The reason I say the price difference is $5.00
RETAIL and I can't see why a Kuhmo would bother making two different tires
to make a percent of $5.00! The sidewalls would reflect the differences
between the D and E but I wonder if actual tire construction would be
different.

Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426

-----Original Message-----
From: gmclist...@temp.gmcnet.org
[mailto:gmclist...@temp.gmcnet.org] On Behalf Of Ken Burton
Sent: Saturday, 5 December 2009 1:09 PM
To: gmc...@temp.gmcnet.org
Subject: Re: [GMCnet] Tires

http://www.tirerack.com/tires/TireSearchResults.jsp?skipOver=true&width=225%

[Ken Burton]

Robert Mueller wrote on Fri, 04 December 2009 22&#58;10

> Ken,
>
> I'd love to see the Load Range D and Load Range E side by side to compare
> all the info on the side walls. I really wonder if there is REALLY any
> difference between them. The reason I say the price difference is $5.00
> RETAIL and I can't see why a Kuhmo would bother making two different tires
> to make a percent of $5.00! The sidewalls would reflect the differences
> between the D and E but I wonder if actual tire construction would be
> different.
>
> Regards,
> Rob Mueller
> Sydney, Australia
> AUS '75 Avion-The Blue Streak TZE365V100428
> USA '75 Avion-Double Trouble TZE365V100426

The written specs are exactly the same EXCEPT weight rating and tire pressure. They both weigh 38 pounds.

[Rob Mueller]

Ken,

Things that make you go Hmmmmm????

Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426

-----Original Message-----
From: gmclist...@temp.gmcnet.org
[mailto:gmclist...@temp.gmcnet.org] On Behalf Of Ken Burton
Sent: Saturday, 5 December 2009 4:18 PM
To: gmc...@temp.gmcnet.org
Subject: Re: [GMCnet] Tires

[Phil Swanson]

I have found that our Costco sells much older RV tires than the local Discount Tire. The problem is Costco doesn't stock our size and has to special order them from a warehouse somewhere where they have sat for up to 6-8 months. Discount stock is fresh because they stock our size. Discount will always match any deal from Costco too.

Phil Swanson
77GMCPB

[Mike Miller]

philipswanson wrote on Sun, 06 December 2009 13&#58;18
> I have found that our Costco sells much older RV tires than the local Discount Tire. ...

While waiting for work to be done at my local low-price tire store, I checked tire codes on the "new" tires. Many where 4 and 5 years old 8o ... others where less than a month.

Buyer Beware.

When "ordering" your tires, specify that they should only be "X" months old. ("X" is up to you.) Then visually check the codes before the tires are mounted.

Do not worry... they'll sell the "older" ones to someone else. :?
--
Mike Miller
`73 26' X Painted D.
`78 23' Birchaven
Hillsboro, OR