ix21@sdccs6.UUCP (David Whiteman) (05/10/84)
I have read in several sources that tire pressure measurements should be made when the tire is cold. Does this mean that the tires should be a certain temperature or simply that the car on which the tires have been mounted had not been driven for a given period of time. I've notice that on a hot day that the pressure can increase just from exposure to direct sunlight on a hot day. Is there a way to compensate for this. David
fish@ihu1g.UUCP (Bob Fishell) (05/14/84)
The rule of thumb is to add 4 psi to a cold measurement to convert it to a "hot" measurement. Look up Boyles' laws for a more accurate computation. However, I thought that tire pressure should always be measured hot, because that's what the tires are when you're rolling. -- Bob Fishell ihnp4!ihu1g!fish
an@hou2h.UUCP (A.NGUYEN) (05/14/84)
-- > Bob Fishell (ihnp4!ihu1g!fish): > .. I thought that tire pressure should always be measured hot, > because that's what the tires are when you're rolling. Tyre temperature (and hence pressure) when underway could vary a lot depending on cold inflation pressure (underfinflated tyres flex more and generate more heat), load, and driving style (four wheel drifts, hard braking, etc), and other factors. Therefore cold pressure is always a more consistent baseline. > The rule of thumb is to add 4 psi to a cold measurement to convert > it to a "hot" measurement. I figure 10 percent of cold pressure. Au