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Air Pressure in Tires

Of course it does. The more weight the tire is supporting, the higher the pressure will be.

I am talking in absolutes terms and not something that needs to be corrected for. Do you mean the same?



Hoop,

Yes, here is a change but, it's not measurable by even the best of gauges.

Sorry man, I was trying to keep it simple.
 
Thanks all, didn't think I would ever get such a strong response. Amazing how adamant each person is on their way of checking air pressure. Sounds like the general consensus is "doesn't really matter, either way works fine". However, I think I'm going with on the ground, cold, with quality gauge.
Funny, that's what I've been doing for years!
 
I think the reason you don't get a measurable change (with most gauges) with the weight on the tire or no weight on the tire is because 1.) The gauge is not that accurate, as said before. But also 2.) as you "squish" the tire on the ground, the rest of the tire stretchs a little, increasing volume to make up for what was squished (a little).

As for checking pressure, I have found that if I check my tires cold in the morning (70 degress), when I come home in the afternoon on a 90 degree day, my pressure is up about 4 psi. So, I think temperature has much more of an impact compared to measureing the pressure with the bike up or down on the ground.

I always wonder what the plus/minus is on the "recommended pressures" given from the tire manufacturers. For example, if I lived in say Phoenix in the summer, would it be better to slightly under inflate my tires to better hit the "recommended" pressure to compensate for the higher pressure from road heat in the day.......I know I am getting all geeky on this but I am just wondering....
 
Good point. Some people will also argue this fact. If you were to remove the tire valve from a rim and let all the air come out of the tire, how many pounds of air pressure will remain in the tire.

An everyday person will say Zero.
A Physicist would say 14.7 lbs.

Who is correct?:)

Depends on your units. If you are talking psia, then 14.7, or whatever the current barometric pressure is. If you are talking psig, then it is zero. Values do not make any sense unless you know what the units are. :D
 
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