Canadian Hummer Club Forums

The manufacturer recommends 30PSI for both front and read, but I wonder if I should inflate the tires a bit more with three passengers in the car on a regular basis. I asked a certified mechanic at Canadian Tire just now and he recommended 35PSI for both front and rear. Can some one share his or her ideas and opinions??? I have a brand new 2008 H3 with standard transmission, which I just brought back from Detroit for a deep discount.

First opinion that I would give is never listen to a mechanic from Canadian Tire!!!! Brainless idiots in my opinion and completely untrustworthy and trained to basically screw you over as part of their income!



Anyways the psi varies depending on the manufacturer... always check the side wall for ratings, and for city driving you want to keep it near the max for fuel eceonomy and then lower for going off road to improve traction and help prevent against damage on rocks...

If you don't run 35psi your little indicator light will come on too



Basically you should be running whatever PSI is indicated on the driver side door jam; UNLESS the sidewall on your tire indicates this is over the maximum PSI.

Our 08 H3 Alpha even  with wider lt285/75r16 still runs on stated psi from the door frame. It should only be lowered if in loose sand for traction.  If you think weight has any effect remember those skinny road bike ( yes pedal bicycles) run at 100 psi in fact my normal one runs at  65-70 psi. 

Bear in mind that the door frame pretains to stock tires..... a vast amount of Hummer Drivers (including myself) swap those out for better offroad use.

You want to lower your PSI for extreme trails as well (Not just sand) as sharp rocks can damage a tire at max psi.... unless of course you are running bias ply tires which I'm not too keen on...

Use the rated PSI from the manu. 

The square inch of tire contact will not change much with the little extra weight of passengers. Do the math, tire foot print say 6 * 8 inches gives 48 sq inches. Times that by 4 tires, gives 192 sq. Times that by tire pressure say 30, gives 5760 lbs weight load.

Taking all this (crap) into account,for every lb of air pressure you can increase the load by 200 lbs keeping the same tire foot print.Or, having the tire foot print about a 1/4 inch wider and longer for a 500 lb load using 30 psi pressure.

Now I have to get a couple of asa's . Too much info! <img src='http://www.canadianhummerclub.com/forum ... >/grin.gif' class='bbc_emoticon' alt=';D' />

Thanks, I guess I will keep all four tires at 30PSI as stated on the door panel from now on for city and highway driving.

I'll leave that analogy alone...  <img src='http://www.canadianhummerclub.com/forum ... >/grin.gif' class='bbc_emoticon' alt=';D' />