Air pressure in 10 ply tires

I'm not an expert on pressure gauges, but I can't imagine one that would read different based on altitude. Pressure is pressure. A torque wrench doesn't have to be calibrated for altitude. Temperature maybe, but marginal difference. That said, using a quality gauge is advised. I ride mountain bikes with fat, tubeless tires, and accuracy at lower pressures is important. Using the same quality gauge for comparison is also advised, don't switch gauges.

 

I bought a $9 digital POS guage from auto zone today and it said every tire in my driveway was 41.5 lbs lol. Took it back and got an old school pocket pen style one and it is more accurate.

 

@splitbolt

So i took the measurements.

• Distance between lowest part of rim to ground is 5".
• Distance between the highest part of rim and top of tire is 5 3/4"
• Distance on the left and right side, from rim to tire is 5 5/8"

Now from my understanding the distances between top of rim to the tire to the lowest part of the rim to the ground should not be the same, as the tire is under load. I guess i should put a few more psi. Ill try 34 front and 32 rear and see how it feels.

Thanks for all the info man, i havent got a chance to look at the charts though. I am really curious about it actually, ill do it this weekend for sure. Happy friday all!

 

Haha! I got the pen style for like 8 years now and it still works great. I would never trust a digital POS.

 

Yes; a certain amount of deflection is to be expected. My point was...don't go by your eyeball.
You might be surprised...
It seems counterintuitive, but 41 psi might actually feel better.

 

I was a bit surprised actually.

41psi cold?

 

Yes.

 

Damn. So when they heat up, it will go up to 43-44psi?

 

Yup

 

Based on your comments, I decided to make sure I was right. Here is one article indicating what I am saying makes a difference..
https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=167

 

Hm. I will try and see how the ride is. Will report back tomorrow as i got the work truck again tonight, working tomorrow


Well i shouldnt complain, i should be happy i got work, ha!

 

Clicked into this thread to see a jar of pee. Ambiguous jar of pee is ambiguous

 

Yes, if you change nothing and take a reading at 5,000 ft, and then at sea level, you will get different readings due to ambient air pressure. This has nothing to do with the gauge calibration and everything to do with ambient air pressure.

 

I don't understand why less contact patch is better. Going by the methodology detailed above, LT tires require more pressure than passenger tires. LT tires also have stiffer sidewalls/tread than passenger tires. Both of these characteristics lead to less contact patch for the same size tire and load.

 

I don't mean this to be a back and forth. Here is another article discussing the difference between Gauge and Atmospheric pressures.

https://www.coyoteents.com/compensating-tire-pressure-readings-for-elevation/?

 

No it doesn't.

 

34-37 and you will be fine.

 

So i did 36 front and 34 rear and it feels the same. I dont know why i said 35 psi felt rough. It was 2 years ago and maybe it was 45 psi? Not sure, but anyways it feels good. Will look into those charts and might adjust pressure later on.

Thanks for all the good input guys, cheers.

 

Yes, thanks, exactly my point. Good calculator at the bottom!