Tire Pressures

[alanrichey]

I may be stating the blindingly obvious here but I certainly wasn't aware of it before.

 

During the summer I fitted a wireless tire pressure monitor and I set all the tires at 18 psi when cold and subsequently found that during driving they warmed up to 19-20 psi, just about perfect. After a gap of a month (on holiday) I just took the car out and found the tires were now 15 psi when cold, warming up to 16-17psi.. It 's obviously caused by the cold weather but I had not realised you needed to top the tires up in the winter.

[fry61]

Just drive harder & the air in the tyre will warm some more!!

[blue]

To find optimum tyre pressure for your car /bike etc pick a starting number like say 30psi

and go for a good drive to warm the tyre .the tyre should go up 10% in pressure any more and starting pressure to low any any less starting pressure to high

takes a while but you get the optimum tyre pressure for your car not a general I run ***** in mine

[IanS]

Universal gas law.

For a fixed amount of gas (sealed tyre)

PV/T=Constant

As the volume is near constant a 27 degree C temperature change is approx 10%

(temperatures are zero at absolute zero)

So the pressure change should be approx 10%

(referenced to vacuum)

3psi change in 15psi atmosphere + 20psi tyre is a bit less but in the right region