Just thought it interesting but I went to take the car out for the 1st time since my April 20th dealer service. I recall the day was cold and rainy . When I checked my tire pressures the fronts were at 36.5 and the rears at 38.5 psi. Yesterday's temps were in the 90's but it was interesting that the pressures were that high. I assumed that during the oil change and NYS inspection that they must have pumped up the tires while cold to the recommended pressures. So just dropped them to 33/35 . All fluids checked and on we go. Funny 93* F yesterday and wake up today to 45*F . Hey then again it snowed in Colorado.

 

Standard rule of thumb is 1 psi for every 10*F. If you checked and adjusted while at 90*F, they're now below spec at 45*F.

 

Tire pressure is affected by both temperature and altitude. When it comes to measuring tire inflation pressure, note that there is a difference between atmospheric pressure and gauge pressure. Tire pressure gauges measure the amount of pressure above the ambient atmospheric pressure.



For a detailed explanation, see: https://www.tirerack.com/tires/tiret...jsp?techid=167


Stuart