tire pressure when empty
Postmaster
Joined: Jul 2003
Posts: 2,628
Likes: 0
From: Calgary, Canada
I've had mine up to about 40# for a while to see if it made any difference with mileage, it didn't seem to so I put them back to about 30 - 32. YOu should be fine to lower them 5 - 7 #. But that's just my opinion and you should run your tires at the pressure stated on the sidwalls.
Cargo Master
Joined: Aug 2004
Posts: 2,899
Likes: 2
From: Lynnwood, WA
The pressure stated on the sidewall is the maximum allowed pressure when cold, and more often than not, tires should NOT be run at that pressure unless they are carrying heavy load.
There are several methods (i.e. chalk) to determine what's the optimal pressure for the tires on a given car. My guess would be 30 - 35 for front, 25 - 35 rear in your case when running empty. Or you can subtract 10% - 20% from the factory recommendation for the front, and use the same, or a little less for the rear.
There are several methods (i.e. chalk) to determine what's the optimal pressure for the tires on a given car. My guess would be 30 - 35 for front, 25 - 35 rear in your case when running empty. Or you can subtract 10% - 20% from the factory recommendation for the front, and use the same, or a little less for the rear.
i ain't rite
Joined: Mar 2005
Posts: 65,449
Likes: 5,518
From: Marlboro Mental Hospital.
while our trucks are nowhere near being close to each other other than the fact they are both fords, i figured i would chime in here anyway 
. i am currently running 36X12.5X16.5 bfg mt radials on the 88 superduty turbo diesel. i run 55 lbs in the front, and 20 lbs in the rear when empty.this gives me full tread contact with the road. i never pay much mind to what the sidewall says, that is max pressure when fully loaded.
i determine a tires best air pressure with a large stick of chalk. i cover an area of the tire, and go for a small ride. then i look at the tire. if there is chalk on the outside of the tread, i air down till it is all gone after a ride around the block. if there is chalk in the middle, i know i need to air up.
. i am currently running 36X12.5X16.5 bfg mt radials on the 88 superduty turbo diesel. i run 55 lbs in the front, and 20 lbs in the rear when empty.this gives me full tread contact with the road. i never pay much mind to what the sidewall says, that is max pressure when fully loaded. i determine a tires best air pressure with a large stick of chalk. i cover an area of the tire, and go for a small ride. then i look at the tire. if there is chalk on the outside of the tread, i air down till it is all gone after a ride around the block. if there is chalk in the middle, i know i need to air up.
Cargo Master
Joined: Aug 2004
Posts: 2,899
Likes: 2
From: Lynnwood, WA
I think everything we post here comes with an implied disclaimer. Most 31x10.50 are 6 ply 50 psi, and on an F150, that would result in a bone jarring ride.
My 95 Bronco has has a recommended pressure of 35/41 (front/rear) for 235/75R15s, but I'm sure 41 is when it's fully loaded, so I normally run 35/35 mostly because of a slight gain in mpg, even though 32 handles and rides a little better. The F150 should be very similar, except it's rear is lighter.
Aside from ride quality, wet stopping can suffer very significantly if the tires are overinflated too much. Probably not an issue right now (damn, I hate 100+
), but it's something to be aware of.
My 95 Bronco has has a recommended pressure of 35/41 (front/rear) for 235/75R15s, but I'm sure 41 is when it's fully loaded, so I normally run 35/35 mostly because of a slight gain in mpg, even though 32 handles and rides a little better. The F150 should be very similar, except it's rear is lighter.
Aside from ride quality, wet stopping can suffer very significantly if the tires are overinflated too much. Probably not an issue right now (damn, I hate 100+
), but it's something to be aware of.
