Tire Pressure question...

[roush9799]

As I look at my door sticker, it says 30 lbs fronts and 35 lbs rear. I would think you'd want the pressures the same on an AWD right? Is the 35 rear for if it's loaded down in the back plus the weight on the hitch? Or do I need to run what the door says all the time? Seems like now that most of the weight would be on the front since I'm using it as a 3 people hauler and occasionally a load of groceries.

 

[xtoolmaker]

Do what the door sticker says.I have a 2003 4 wheel drive xls and I have had excellent tire wear following the factory PSI.Also rotate every 5,000 miles and check the pressure often.With all the Firesone tire ,rollover trouble Ford had with the Explore they worked hard to come up with a good setup for the third gen.

 

[jrford]

i've got an '04 AWD, i keep them at 35psi i think mine has them all the same. . .
Got 5yrs/50k on a set of Michelins with about 50% tread left, doing a 5 tire rotation however. No problems with the Viscous clutch.

 

[jadatis]

Tire-pressure advice is all about load on the seperate tires.
A little bit about speed and even less about camber angle ( alighnment tires like this /-\ instead of this |-|) .
So if you can determine the loads on the seperate tires exactly , you can calculate the needed pressure for that , preferably with some extra load for savety-margin.
a
This load is not that easyly to determine, and if you can, there is another problem.

By the Ford/Firestone affaire they discovered that some tires , those with large rubber segments on the side for rough terain, are not allowed to flex that much, and so the maximum load of those tires is to high calculated.
I first thougt that it was the wrong calculation that was done in America before 2005, but that was adequatly repaired by lowering the maximum load for standard load tires for SUV.

so if you give your tire data ( maximum load xxxx lbs AT yyy PSI (cold) written on the sidewall , or kind of tire and if it is such a tire for rough terain, and the GAWR's of the car, i can calculate for you the needed pressure.
For normal use you want, I need the empty weigth of the car and weight devision front/back ( motor in front , front of backwheeldrive) , so I can estimate the actual loads on the axles .

I got interested in tire-pressure when I had an RV, and got hold of the pretty save European formula to calculate pressure for a sertain load.
Later discovered the differences between Europe and America and a saver formula described by an American.