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Discussion Starter · #1 ·
Just wondering....The B5's numbers in the fuel door are based on Cold. I often think of filling them after the long drive home, when the tires are nice and toasty! :D
 

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Macabre recalls some of his Chemistry. Pressure must be absolute not gauge and temperature must be in degrees Kelvin or starting at absolute zero. Part of the gas laws The volume of the tire also expand a bit. Too complex ! Try to remember to inflate when cool.
 

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Discussion Starter · #5 ·
Yeah, I know extreme temps like racing tires are a whole nuther ballgame. But for average road driving, I expect a ballpark idea.
 

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Macabre said:
P1/P2 = T1/T2... however, you can't rely on that, because humidity has a significantly more complicated effect.
true, but you'd have to figure out the temperature inside the tire. but if you can figure out the tempurature, be sure to use absolute tempurature (rankine or kelvin). of course, you're assuming you're working with an ideal gas.
 

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JETninja said:
Just wondering....The B5's numbers in the fuel door are based on Cold. I often think of filling them after the long drive home, when the tires are nice and toasty! :D
You could do what I do...I add, say, 4 or 5 PSI when I get home and there's still some daylight to work with. Then, in the morning before I move the car, I deflate the tires to whatever pressure setting I want. The tires are cold and you can set them perfectly. Just don't overshoot on the deflation!
 
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