I know this question is about tires, but since it is not concerning aftermarket tires, I thought I'd stick it in here... I noticed this last weekend on the sticker in the driver's side door jam/well where it gives the vehicles GAWR and other info., that it recommends putting 26 psi cold for the front tires and 30 psi cold for the rear tires for P275/60-R17 tires. (I just bought a new set of the Goodyear Eagle GTII's that came stock on the '98 STX's.) The maximum recommended cold pressure for these tires is 44 psi. I've ran 35 psi cold front and back for the last 80,000 miles on 2 sets of the same tires, and both ended up wearing out the centers of the tires moreso than the outside (suggesting they were over inflated at 35 psi over the life of the tire.) My question is this: Why does Ford recommend less pressure in the front than in the back? It would seem like if anything since there's far more weight in the front that unless you were hauling a lot of weight in the back (which I don't) that you would want to put more air in the front tires, not the other way around. Can anyone explain this?

I've tried running my tires at the recommended pressure (26 in the front and 30 in the back) and while I'll admit there's all the difference in the world in the smoothness of the 'ride' the truck handles so sloppily that in my opinion it's not worth it.

 

My "guess" is that Ford has the rears at a higher psi because they don't expect people to actually adjust it for a "loaded" situation.

I don't know where they came up with those exact psi numbers either....... They seem pretty low to me too.

I do know a tire will get much hotter running a lower psi then one running a higher one. Found that out on my little 4x8 utility trailer. Had only 40 psi in one tire and loaded it up. Traveled only 5 miles and never got over 45 mph and when I got home that tire was so hot, you could not leave your hand on it. Pumped it up to it's cold psi rating of 60 and got another load. The tire was only warm to the touch that time around.......

I have LT load range C tires and the max cold psi is 50 for them. I do adjust them for load conditions, so I run my fronts at 44 and the rears at 40 for everyday empty conditions. When I load up the bed, I'll bump the rears to 50.

Even though the center of my tread is visually higher then the sides, I'm getting pretty even wear as far as I can tell. Got over 25k on them (50k mile life) and they are by no means 50% worn. I just rotate them every 5000 miles or so.

You'll get all kinds of "advice" on what pressure to run. All I can say is run what feels best to you. Took me awhile to find a pressure that satisfied my handling requirements and ride quality level. I would have thought that 35 psi up front would have been fine for your tire ratings. Even for the tire wear factor.......

 

Basically 35 psi should have been ok.

However, for myself I look at the sidewall bulge. There should be a small bulge when you're truck is sitting on flat pavement. If the ride appears to firm for you let some air out but personally I wouldn't go much below 30 psi otherwise they'll run hot. My new 275/17 AT/S rubber runs good at 35. I came back from the Goodyear dealer with 38 psi in them and the ride was just too firm and they wandered a bit. Wear seems even so far but too early to tell.

If you're running lower profile tires (wider) the pressure can be somewhat more critical as overinflation will bulge out the centre of the tread and cause it to wear rapidly.

Some people say 32 psi is ideal.

If you've got a ton of weight in the back then bring the back tires up to close to their maximum pressure rating or your sidewalls will be squirming around on corners. (ie. dangerous)

As a rule I usually pay more attention to the tire sidewall than the door sticker.

26 psi sounds way too low, but that's my opinion.

Off-road I used to run down to 10 psi with 33/12.5/15inch B.F.Goodrich Mud/TA's on an 82' Toyota 4x4.

The larger the internal air volume of a tire, the larger the load you can carry at the same psi rating compared to other tires.

 

I agree, you'd think 9 pounds off the maximum (44 max to 35 psi) would be plenty, not to mention I like the way the truck 'feels' at 35 pounds. However as I mentioned on two different sets of tires the centers would be worn out completely with no tread left at all while the sides wern't even quite worn down to the warning bars. I'm trying them at 32 pounds all the way around right now... It's suprising how much of a difference you can tell both in the quality of ride aswell as the lack of handling as you go down by just a few pounds...

 

The way I understand it, the suggested tire pressure on the door is for the best combination of comfort, milage and usability. I too was running mine higher since they did recommend 44 psi but it road like a buck-board. I lowered the pressure to the door recomendation and the truck is much more comfortable. I don't think either way should effect the tire wear.

 

My tires have a 44 PSI max rating too. When I am unloaded I run 35 psi in them. Thats what Goodyear recommends. Of course loaded ***** To The Wall, 40-44 psi will do just fine.

 

Was the pressure on your door recommendation the same as mine? (26 in the front/30 in the back)? If so, have you been thry a whole set of tires yet to see how they wore with tires at that pressure?

 

Running soft 26 psi will wear the tires out in a hurry.