Tyre Pressures

Less than 4psi = to high initial pressure.
Over 4psi = to low initial pressure. .... Reason being to low a pressure=more flex=more friction=more heat=increase in pressure.

If the pressure has increased by less than 4 lb the pressure was too high to start with. As a matter of interest What size are your tyres, brand and what pressure are you running? I always train people in their own car and I am constantly surprised at the high tire pressures people tend to run in the mistaken belief more pressure means less punctures. The correct pressure allows the tire to conform to the terrain and also become a factor in suspension resulting in a more compliant ride.
Cheers RobCairns Offroad Training & Tours

Some people may be running pressures too high..... but there are far more are running too low, atleast as far as family hacks for the bitumen. Yes they need to be lowered for off road, but when back on the bitumen they should go up again. Running proper pressures (at the UPPER limit of recommended book pressures) will give better handling, stopping and tyre life, with even more difference noticeable in the wet, as dynamic aquaplaning speed is directly correlated to tyre pressure (higher tyre pressure gives higher aquaplaning speed).
When r,unning lower pressures, all of the above will suffer badly- only benefit will be a slightly smoother ride.
Moral of the story is check your pressures more often, and run them on the high side of recommended. By all means lower them off road- but beg steal or borrow a compressor and pump them back up ASAP when you back on the tar.... I'll bet anybody a carton or two there are more people driving around with pressures too low rather than too high (and ALL the motoring associations eg NRMA etc agree with me )

Interested in all this tyre pressure business. Has anyone any knowledge of the term 'Static Load Radius'? The SLR is a figure published by the tyre manufacturer for all their model tyres. It is a constant figure no matter what the load. That is the tyre radius is measured with any given load and the pressure adjusted to match the given figure for your tyre. Adjustments have to be made for tyre wear and road surface but it does give a good starting point that I have found very useful.

The static load radius measurement is available but often only from the technical departments. I have Hankook tyres and they do publish a good detailed guide to their tyres. It does not however give the SLR measurements. I obtained the measurement from the tyre store. They had a more sophisticated guide. It is a measurement worthwhile following up and I should think that the technical department of any tyre manufacturer should be able to let you know the value for any of their products. It does not surprise me that the tyre sellers don't know of this measurement. It is however available. Good luck