For years I've been using a method to work out the best tyre pressures which I was told was originally from Michelin.

Inflate your tyres to the desired pressure then go for a drive long enough to warm the tyres up. Best to do it on the highway driving at your normal speed.

Check your tyre pressure, if it is now about 4 lbs higher you've got it right.

If the pressure increase is less than 4 lbs you need to drop your cold pressures.

If the increase is greater than 4 lbs you do not have enough air in the tyres and should increase the cold tyre pressure.

Cold tyre pressures will need to be adjusted for varying loads, speeds and uses and even different weather conditions (summer/winter).

You will find that while someones elses pressures may be a guide they will differ from yours due to different vehicle weights (some like me carry a lot of gear in our trucks), travelling at different speeds and different types of road surface.

After a while you will find that you will be able to pick the pressure suitable for your truck in your type of use.

I use the 4 lb rule in my cars too with great success.

All you Hummer owners with CTIS have it easy with adjusting tyre pressures you can do it on the go.

On my Humvee I have found that 35lb is about right for my load and cruising speed with 37" GSA's, but I'm a bit lighter than a Hummer.

Peter J.
Sydney, Australia
RHD M1026 Humvee