Tire Pressure Question

[RichS]

For those of you who ride 700 x 32-35 size tires (with tubes) on roads, what is the minimum tire pressure you're comfortable using? 

I realize there are factors such as rim width, tire compound and rider weight that influence this. Many thanks for your feedback!

Best regards,

Richard

[Bill Lindsay]

40psi

[Rod Holland]

I ride my 32mm Stampede Pass Extralights inflated to 60psi front, 65psi rear; 235lb rider. I have no doubt I could run them at a somewhat lower pressure. I remember a long period of experimentation with GB Cypres ELs, looking for the lowest sensible pressure, that ended when I started getting pinch flats. In the years since, I've settled on 60/65 in that size range, and been happy. I'd run 35mm tires somewhat lower.

rod

[Virgil Staphbeard]

I ride my 32 GB Cypres at 40/45 F/R and I weigh 135

On Thursday, May 24, 2018 at 10:40:57 AM UTC-4, RichS wrote:

[Garth]

The minimum is the low 30's for me with 35mm tires.  I don't check them every day, maybe once a week or so or whenever whenever happens.  When I re-inflate I'll go about 40-43 rear and 35-38 front, then don't check again(visual and feel yes, gauge no) until I do !   

The tires are Performance Forte Metro-K(for kevlar belt) on Mavic A719 rims(19mm inside/24.5mm out). I have no idea what I weigh, it could be anywhere from 150-180 pounds, you got me.

On Thursday, May 24, 2018 at 10:40:57 AM UTC-4, RichS wrote:

[nash...@gmail.com]

If you don't have enough familiarity to decide this on your own, it always says on the side of the tire. Not trying to be snarky.

[R Shannon]

Nash, interesting reply. I know what it says on the side of the tire.

Like others on the list I’m prone to exploring other possibilties beyond the manufacturer’s more conservative recommendations. Just curious to find out to what degree others have deviated in their experiments with tire pressure.

At 150lbs. so far so good in the 35-40 psi range. Greatly appreciate everyone’s feedback.

Best,
Richard



Sent from my iPhone

> On May 24, 2018, at 12:26 PM, nash...@gmail.com wrote:
>
> If you don't have enough familiarity to decide this on your own, it always says on the side of the tire. Not trying to be snarky.
>

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[Coal Bee Rye Anne]

I've mostly ridden 700x33 Challenge Chicane open tubulars(skinwall clincher version) and 700x35 Schwalbe Sammy Slicks the past couple of years and usually inflate to about 50psi but have let them get pretty low (in the high 20's to low 30's) by not checking every ride and only topping off when I notice they are getting noticeably low.  The Challenge tires I believe have 30psi min and the Schwalbe Sammy Slicks might be 50psi min if I remember correctly but I've been riding my Clem lately anyway so not 100% certain of their specs.  Either way, I've mostly ridden them both with approximately the same pressures and at 215lbs and riding them mostly on local gravel and multiuse paths they've fine for me in that 30-50/60psi range. 

Brian Cole

Lawrenceville NJ

On Thursday, May 24, 2018 at 10:40:57 AM UTC-4, RichS wrote:

[Reed Kennedy]

I run the Grand Bois Cypres EL (marked 30mm) and the Compass Stampede Pass EL (marked 32mm) interchangeably on my MAP. Both measure almost exactly 32mm when installed on Velocity A23 rims.

60 psi front, 70 psi rear. Rider: 200 lbs. Front load: 5 lbs. Rear load: None.

Performs great. I'd probably drop those pressures by about 5-10 psi each for a 35mm tire.

I highly recommend the Edison Gauss tire pressure app (available for both iOS and Android), which is based on research done by Frank Berto and followed up by Bicycle Quarterly: http://www.edisongauss.com/index.php/berto-tire-pressure-app/

I'd seriously recommend against running the pressures shown on the sidewalls. As discussed here and elsewhere at length, those are maximum pressures, not optimal pressures. Would be like driving exactly the speed limit all the time, without regard for corners or conditions. Perhaps possible, but certainly not ideal.

Best,

Reed 

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[Reed Kennedy]

On Thu, May 24, 2018 at 9:53 AM, Reed Kennedy <re...@notfine.com> wrote:

I run the Grand Bois Cypres EL (marked 30mm) and the Compass Stampede Pass EL (marked 32mm) interchangeably on my MAP. Both measure almost exactly 32mm when installed on Velocity A23 rims.

60 psi front, 70 psi rear. Rider: 200 lbs. Front load: 5 lbs. Rear load: None.

And in case anyone is curious, here are the tire pressures I run on my other bikes, similar loads: 

32mm: 60 psi front, 70 psi rear

38mm: 45 psi front, 55 psi rear

42mm: 40 psi front, 45 psi rear

48mm: 35 psi front, 40 psi rear

On the 38mm tires and up I'll drop the pressure by up to 10 psi when riding offroad. (I don't ride the bike with 32mm tires offroad.)

Best,

Reed

[Patrick Moore]

I am for 50 psi, and have ridden such tires as low as 40. 175.

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[Peter White]

On Thu, May 24, 2018 at 12:26 PM, <nash...@gmail.com> wrote:

If you don't have enough familiarity to decide this on your own, it always says on the side of the tire.  Not trying to be snarky. 

The pressures shown on the sidewalls of most tires are way too high. I've seen 23mm tires rated to 120psi. Sure, the tire may stay on the rim, but there's no reason to run them that hard. And it can lead to premature failure of the rim.

On my Rambuillet, I use the Challenge Parigi Roubaix which have a stated width of 27mm, but measure 29mm when new, and 30mm after a few hundred miles. I weigh 170lbs and run them at 60psi front and 75psi rear. I have arthritis in my spine and if I'm feeling a bit sore, I'll drop the PSI by about 10. 

--

Peter White

[Jim Bronson]

I ran 700x23 Michelin Pro 2/3/4 Race Service Course at 120psi for years, never had any rim failures directly attributable to that.  I had a sidewall failure once but i booted the hole with a $20 bill and made it home alright.  These were for a go-fast bike I don't have anymore, that had tight clearance with 23mm tires!  I was thinner then, more in the 230-250 range.

Back on topic...I run 700x38 Barlow Pass standard sidewalls (I know, a little bigger than you asked) on my Redwood at 50psi front, 55psi rear.  Rider weight 300+.  I don't know exactly how much the + is because I don't weigh myself that much.  I'm sure my performance on the 74 mile ride I'm doing on Saturday will let me know.

Jim

Austin, TX 

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[nash...@gmail.com]

Sorry for replying with an "interesting" reply. I assume you dont actually find my reply interesting.

I dont know your level of experience with bicycles. Many people experiment with tire pressure and there are so many variables, as you pointed out, that it is a highly specific question.

Without any specifics, does the answer have meaning? I used to run my tires at 45/40. Now I run them 60/55.

[tc]

Wife's Sam has barlow passes (regular, not el) on alex dm18 rims.  She runs them at 40 front, 42-44 rear.  Like butter...

Tom

On Thursday, May 24, 2018 at 10:40:57 AM UTC-4, RichS wrote:

[Jon Dukeman,central Colorado]

RichS

Thanks Rich for posting your question as I probably run pressures higher than needed because I would rather live with a stiffer ride than have pinch flats.

Great to hear what pressures others are running. Thanks for sharing. Very helpful!

Nash..... You're a freekin'  Genius!! Who would of thought to look on the side of the tire for Min/Max pressure?? Thanks for that helpful tip.

Jon

[nash...@gmail.com]

Lol who would have thought people wouldn't know how to pump up their tires.

[Jon Dukeman,central Colorado]

Lol Obviously you did☺

[nash...@gmail.com]

Hey ask a stupid question, get a stupid answer

[R Shannon]

Glad the tire inflation question has been answered.

Thanks to everyone! Next topic.

Richard

Sent from my iPhone

> On May 24, 2018, at 10:01 PM, nash...@gmail.com wrote:
>
> Hey ask a stupid question, get a stupid answer
>

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[Nick Payne]

I weigh 140, and I run Challenge Strada Bianca (32mm wide on my rims) at 40psi front and 60psi rear.

Nick

[John Hawrylak]

Rich S asked

what is the minimum tire pressure you're comfortable using? 

Minimum is 75% of the pressure predicted by 15% Tire Drop method based on Front/Rear weight.  Based on a survey I did on iBob group in 2016 or 2017. 

John Hawrylak

Woodstown NJ 

[Deacon Patrick]

John, the non-numeric answer I’ve found most helpful is: enough air to not get snake bite (pinch) flats, not so much air that the cushion requires extra weight to kick in. Grin. If you don’t ride rough stuff, you’ve got a wider range and less risk of snake bite flats.

Nash, not a stupid question, though you appear to specialize in the corresponding answer. Sardonic grin. Grant and Co. cover it in the new catalog. Jan and Co. tested it extensively and changed the cycling industry because of it. If it helps, snark is easily treated. Inflate tires to max pressure listed on the side wall. Ride gravel roads. Grin.

With abandon,
Patrick, who now ponders if his own snark needs treatment. Oops. Sardonic grin.

[John Hawrylak]

Deacon

I agree with your experimental method, especially for non paved roads.  My 75% value was an attempt to provide the same protection against snake bits and ensure the tire does not collapse for a range of total weights and tire sizes.  I forget to mention it was for paved roads. 

John Hawrylak

Woodstown NJ 

[Ron Mc]

Minimum pressure is dictated by two things - enough pressure to protect the rim from shocks, and enough to prevent hinge at the bead, the cause of pinch flats.  You feel it in your butt if you're getting hinge - the bike keeps cornering even though you've steered to straight.  

[Adam in Indiana]

Just for the sake of posterity:

Pasela 35mm, standard up front, TG in back, on Sun M13II rims, 220 lb rider. 65 lbs front, 75 lbs back. It often goes lower than that, though; I check them perhaps every other week, and air them up to those numbers, good for another few weeks...

[John Hawrylak]

Adam

15% Tire Drop pressure is 55 psig front,  67 psig rear, so letting it go low is not bad

John Hawrylak

Woodstown NJ

[John Rinker]

Hey Rich,

Here's a Google Spreadsheet calculator based upon the same research from Bicycle Quarterly mentioned by R. Kennedy above: 

Tire Pressure Calculator

Cheers,

John

[Ray Varella]

Rich,
My method is far more crude than any of the suggestions you have received.
I run my tires as low as I can without having them wash out during hard cornering or bottoming out over bumps.
I nearly always bleed off a little air after pumping them up once I ride a block or two and realize they are too hard.

YMMV
Ray

[R Shannon]

Such much good information here to experiment with. From the mathematical to the crude. Love it:-)

Thanks again everyone!

Richard Shannon 

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[Chris Corral]

150 lb rider, I run 40 front 45 Rear. It is a miracle I have not suffered a pinch flat though. I have tubeless 35c Gravel Kings on non-tubeless rims with a tube inside. 

On road, I'll pump it up closer to 50. never any higher than 55 though.

[John Hawrylak]

Chris

15% Tire Drop pressure is 40 & 48 F/R for 150# rider.  So you are only 3 psig (6%) low in the Rear.  Typically pinch flats occur at pressure 25% lower than 15% tire drop pressure, in your case BELOW 30/36 psig F/R

John Hawrylak

Woodstown NJ

[Chris Corral]

Good point, forgot to apply that formula. I was going by feel, but I trust the science. :)