[GMCnet] What size tires/wheels you guys running on??

[John Fleming]

So, something like P150/40R14H?? :d

What size tires/wheels you guys running on?? Please, give me ALL the specs. The more the merrier. Thanks.


Somewhere on bdub (dbub??), what ever... Somewhere there was an image of a wheel cross section. I can't find it again. Anyone got a link?? Thanks.


.

--
John Fleming
http://www.coldnorth.com/johnnycrash/MMI/GMCMH
Building my own GMC Motorhome from scratch. Problem is, it's only 1/25.
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[John Olson]

Tire
Size



Article
Number Appr. Rim
Width Overall
Tire Diameter Tread
Depth Tire
Weight

LT225/75R16



189752 6.0-7.0 29.3 14
36


Firestone Transforce HT



John Olson
76 Edgemont
Chicago, IL (currently nomadic in AZ)

[Terry]

P tires are for Passenger cars- not for use on GMC except in emergency.

I run Kelly tires
Safari ATR
225/75 R16
load range E
--
Terry Kelpien
73 Glacier 260
Smithfield, Va.

[Robert Mueller]

Terry,

When I bought The Blue Streak I was really happy as it had six brand new tires and a new spare. I drove it about 150 miles from
country NSW to Sydney and it was all over the road!

I didn't know diddley squat about GMC's at the time and when I looked at the tires I noticed they were "P" rated. I checked the
pressure and they were inflated to the max @ 45psi. After a bit of research I found out the tires should be LT.

No wonder it was all over the road! I replaced them with NEXEN LT225/75 R16 All terrain which I inflated to 65 front / 60 rear. Made
a HUGE difference in the way it handled.

Regards,
Rob M.
Sydney, Australia

[Thomas Phipps]

LT 225/75 R 16. On OEM16" Steel Wheels.
Chinese imports from Wal-Mart, 3,500+ places to honor warranty.
Tom, MS II
--
1975 GMC Avion

[Johnny Bridges]

Cooper Discoverer II LT 225 75R16 on Kanomata Specials.  Load range E, and around 65 PSI.
 
--johnny

[John R. Lebetski]

In the sig he says 1/25th Scale model?
--
John Lebetski
Chicago, IL
77 Eleganza II
Source America First

[John Fleming]

Bullitthead wrote

> P tires are for Passenger cars- not for use on GMC except in emergency.

Didn't see the smilie?? Look at that tire I specified... All you took from that was the "P"?? 8o

So, it looks like 225/75R16 are the staple. Makes sense to me. When I had my '83 Merc Marquis, I ran 235/70R14. Nice ride. I miss that car. Anyways...

I guess I should have asked about off-set as well. I have seen everything from what looks like 0 to +10". What is the advantage to running such a great off-set?? Doesn't that mean you need new wheel hubs or spacers, adding to the cost and maintenance issues??

Has anyone ever ran duallies?? With that +10" off-set, bolting up a second wheel seems like the next (il)logical step.

.
--
John Fleming
http://www.coldnorth.com/johnnycrash/MMI/GMCMH
Building my own GMC Motorhome from scratch. Problem is, it's only 1/25.

[John Fleming]

JohnL455 wrote

> In the sig he says 1/25th Scale model?

Yup. This is all research on building the ultimate 1/25 scale model kit of the GMC Motorhome. And then the EM-50 from Stripes (1981). But, I also love this vehicle. And I do hope to one day own one. But... 1/25 is more likely. Oh well.


http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&goto=236957&rid=4262#msg_236957

http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&goto=237977&rid=4262#msg_237977


http://coldnorth.com/johnnycrash/MMI/GMCMH/

http://coldnorth.com/johnnycrash/MMI/GMCMH/R&D/

.

--
John Fleming
http://www.coldnorth.com/johnnycrash/MMI/GMCMH
Building my own GMC Motorhome from scratch. Problem is, it's only 1/25.

[Emery Stora]

On Feb 5, 2014, at 8:51 AM, John Fleming <johnf...@coldnorth.com> wrote:

>
>
> Has anyone ever ran duallies?? With that +10" off-set, bolting up a second wheel seems like the next (il)logical step.
>

Years ago I saw a GMC on a beach with two wheels on each side of the front. The fellow said that gave him good traction in the sand. He would mount two spare tires back to back on his spare tire carrier and mount them to the front when he needed them.

Emery Stora
77 Kingsley
Frederick, CO

-20 ° F at 7 am. Expected to hit +7° by 2 pm

[Corley Wooldridge]

Something to think about: Some states are now implementing checks for tire age. For example, in Oregon, if a truck or motorhome is stopped for anything, or in an accident, the SP probably will check the age of the tires. If the date code makes them more than 7 years old, there is a deep fine. 7 years is the recommended max age for a tire carcass now.

Since you will have to replace your tires in 7 years, a) make sure you are purchasing fresh tires when you buy new ones. b) consider if you want to pay for the best ones out there, then throw them out with full tread left after 7 years (You will probably never wear them out in that time). c) Consider where you could get a guarantee honored when you are on the road, away from home.

Finally, check the load rating, keep them air'd to the recommended pressure, and get only LT tires, not P.

All in all, motels are cheaper... :d

[1275g...@gmail.com]

tphipps wrote on Wed, 05 February 2014 09:34
> On OEM16" Steel Wheels.
> Tom, MS II


OEM was not 16.

OEM was 16.5

I am running 16.5 steel rims painted black.
Firestone HT transforce
8.75R 16.5LT load range E
Blackwall at 65lbs



--
Adam Raeburn
Rothesay, NB
1976 Austin Mini
1977 GMC Palm Beach
---------------------------------------------------
Once you replace everything that is attached to something else. It will all be fixed.

[Larry]

I am running 16" Alcoa's with 245-75-16 Michelin LTX MS tires. One size large than stock. The only reason for the larger tire is...I like the look. A little vain here...but what the hell...I'm 68 and know what I like.
--
Larry :)
78 Royale w/500 Caddy
Menomonie, WI.

[Daryn]

I also have 245-75-16 That the PO had on the Alcoa's. They are just about aged out and i will go back to the stock 225 size. I agree with Larry that they look good but I don't like the lugging and the speedo is also off. I have the stock 3.07 FD. Maybe if I had somthing else I would keep them.
--
1975 Eleganza II
Hudson Valley NY

[Dan Gregg]

I am with Larry, I love the look. I run over sized tires on all of my vehicles. 245-75-16. 355 final drive and a screaming 455 with Holley TBI.
Dan
--
Dan & Teri Gregg
Dexter, Mo.

http://danandteri.blogspot.com/

[mike foster]

225/75/16 on Eagle Allow Forged rims. Uniroyal Laredo HD/H load range 'e'&#8230;.. because my brother in law could save $60 per tire for me&#8230;.Yeah, I know, world class cheap skate but I just couldn't see the extra $$$$ for Michelin when the blue bus never sees more than 65 mph and the tires will age out long before they wear out.

[Bob de Kruyff]

mikethebike wrote on Wed, 05 February 2014 14:14

> 225/75/16 on Eagle Allow Forged rims. Uniroyal Laredo HD/H load range 'e'&#8230;.. because my brother in law could save $60 per tire for me&#8230;.Yeah, I know, world class cheap skate but I just couldn't see the extra $$$$ for Michelin when the blue bus never sees more than 65 mph and the tires will age out long before they wear out.

Uniroyal is a Michelin company and recent experience at this end shows them to be excellent tires.
--
Bob de Kruyff
78 Eleganza
Chandler, AZ

[Robert Mueller]

John,

Here's a link to the specs for Alcoa wheels for a GMC:

http://www.gmcmhphotos.com/photos/random-photos/p46735-alcoa-wheels-for-a-gmc.html

The front track is narrower than the rear track; here's a link to spacers that you install to bring them into alignment:

http://www.appliedgmc.com/prod.itml/icOid/656

Regards,
Rob M.
Sydney, Australia

-----Original Message-----

From: John Fleming

So, it looks like 225/75R16 are the staple. Makes sense to me. When I had my '83 Merc Marquis, I ran 235/70R14. Nice ride. I miss
that car. Anyways...

I guess I should have asked about off-set as well. I have seen everything from what looks like 0 to +10". What is the advantage to
running such a great off-set?? Doesn't that mean you need new wheel hubs or spacers, adding to the cost and maintenance issues??

Has anyone ever ran duallies?? With that +10" off-set, bolting up a second wheel seems like the next (il)logical step.

John

[Thomas Phipps]

I am very well aware that GMC Motorhome OEM wheel is 16.5". However, I have a complete set of GMC Dually Pick-Up 16" Steel Wheels, therefore the "OEM" content.
Tires are also Losd Range E.

Tom, MS II
--
1975 GMC Avion

[George Groth]

I also run the 245's mentioned above, BFG. I saw an improvement in handling, no rut running when I changed over. I think the bigger tires make the coach handle better.
--
geo groth '73 260 Sequoia
Carson City Nevada 89703

[1275g...@gmail.com]

tphipps wrote on Wed, 05 February 2014 21:09

> I am very well aware that GMC Motorhome OEM wheel is 16.5". However, I have a complete set of GMC Dually Pick-Up 16" Steel Wheels, therefore the "OEM" content.
> Tires are also Losd Range E.
> Tom, MS II

I figured you did just wouldn't want some newby buying a GMC and trying to put 16" tires on 16.5" rims.

I had load range D on when I got the rig and it always felt floaty no matter the air pressure in the tire. the heavier tire feels so much better.

--
Adam Raeburn
Rothesay, NB
1976 Austin Mini
1977 GMC Palm Beach
---------------------------------------------------
Once you replace everything that is attached to something else. It will all be fixed.

[mike foster]

USAussie wrote on Wed, 05 February 2014 17:02

You might want to rethink offsetting the front wheels to push them out to the edge of the wheel opening. The bearings are running right around 80-90% of max load as is and if you space them out it will put the load well over the limit. There is a very good article on one of the GMC sites with all the engineering data.

Back in the 60's-70's guys ran chromed/reversed rims to do the same thing. I never did for that reason.

[Bob de Kruyff]

""You might want to rethink offsetting the front wheels to push them out to the edge of the wheel opening. The bearings are running right around 80-90% of max load as is and if you space them out it will put the load well over the limit. There is a very good article on one of the GMC sites with all the engineering data. We won't even go into what moving the centerline of the wheel that far out will do if you have a front tire go down.

Back in the 60's-70's guys ran chromed/reversed rims to do the same thing. I never did for that reason.

[Updated on: Thu, 06 February 2014 08:24]

""

Mike, I was in that same camp when I first heard about doing this years ago. However, I think dozens of GMCer's have proven me wrong on that point.

--
Bob de Kruyff
78 Eleganza
Chandler, AZ

[mike foster]

I'm leaving my rims with the factory offset. It's my understanding these have a negative roll radius and moving the rims out to match the rear changes that to a positive roll radius and my way of thinking is the engineers know a lot more than most of us. I'll admit the wheels look better out there, but I'm inside the thing!!

[Robert Mueller]

Bob,

Agreed!

This is a horse that has been beaten to DEATH here over the years every time a newbie arrives it starts over again.

However, it has been sited correctly that installing the wheel spacers exacerbates any steering / alignment issues.

Regards,
Rob M.
Sydney, Australia

-----Original Message-----

From: Bob de Kruyff

Mike, I was in that same camp when I first heard about doing this years ago. However, I think dozens of GMCer's have proven me wrong
on that point.
--
Bob

[Bob de Kruyff]

mikethebike wrote on Thu, 06 February 2014 19:11

> I'm leaving my rims with the factory offset. It's my understanding these have a negative roll radius and moving the rims out to match the rear changes that to a positive roll radius and my way of thinking is the engineers know a lot more than most of us. I'll admit the wheels look better out there, but I'm inside the thing!!

There definitely are some geometry changes that go along with this mod--the biggest one is effective spindle length that can affect torque steer. Some, but not all have noted a change. Other parameters such as toe change, camber compensation, roll steer, roll center height, are not affected by this change. On paper, pitman arm loads should go up as well as steering feedback, but most people are not experiencing those problems either.

--
Bob de Kruyff
78 Eleganza
Chandler, AZ