Tire PSI

I use a little technique I got from this forum several years ago. Start with cold tires, empty truck and inflated to door sticker pressure. Find two pieces of something thin, flat and straight. Place them under each end of the tire where it contacts the pAvement. Measure the distance, making sure to square it up. Add whatever load you're going to have and repeat the process adding air until you get back to the first distance.
It has worked well for me. Tires wear evenly, ride is good and it handles well.

Ford recommends my OEM LT245/75R17 E tires have 55# in front and 60# in rear. So my truck stays at that level, towing or not towing.

Cummins12V98 wrote:

Golfcart wrote:
My dad and I have an ongoing debate about which to follow. Personally I like to keep my tires at the sidewall max pressure, even when not towing.

On a 1500 that is actually a good idea if you are running "P" tires. If "E" you will have a very rough ride and wear the centers out FAST.

I run my Tahoe 44 front and 40 rear and get great tire wear. Door says somewhere in the mid 30's but that is for ride quality.

I do admit the ride is a bit crappy compared to my dads running 32psi, but its a truck after all, I dont expect it to ride like a town car!

42-44psi front and rear gives me consistent wear and less risk of tires running hot

peaeye1 wrote:

rhagfo wrote:

peaeye1 wrote:

2oldman wrote:
80

Finally, a firm answer, but what I am curious about is why the numbers on the door are different. I was going with the 80 anyway.

Too bad it is wrong!
Unless you want the truck to ride like the Flintstones car!:S

After further review of all the input, I believe I will go with the door sticker 75/65, unless I change my mind :B. That PSI rides good.

Good call if towing at the axle rating or close to it. Running Solo you will be wearing the centers on the rear tires for sure! Try 35-40 running empty.

Golfcart wrote:
My dad and I have an ongoing debate about which to follow. Personally I like to keep my tires at the sidewall max pressure, even when not towing.

On a 1500 that is actually a good idea if you are running "P" tires. If "E" you will have a very rough ride and wear the centers out FAST.

I run my Tahoe 44 front and 40 rear and get great tire wear. Door says somewhere in the mid 30's but that is for ride quality.

rhagfo wrote:

peaeye1 wrote:

2oldman wrote:
80

Finally, a firm answer, but what I am curious about is why the numbers on the door are different. I was going with the 80 anyway.

Too bad it is wrong!
Unless you want the truck to ride like the Flintstones car!:S

After further review of all the input, I believe I will go with the door sticker 75/65, unless I change my mind :B. That PSI rides good.

peaeye1 wrote:

2oldman wrote:
80

Finally, a firm answer, but what I am curious about is why the numbers on the door are different. I was going with the 80 anyway.

Too bad it is wrong!
Unless you want the truck to ride like the Flintstones car!:S

Bionic Man wrote:

lbrjet wrote:
Your rears are rated at 2535 per tire in a dual application at 65 psi. Your fronts are rated for 3020 per tire at 75 psi. Both psi's exceed your axle ratings. Ford's recommended tire pressures always assume a maximum load.

Best answer so far. Having a drw with 80 psi in the rears will create a needlessly rough ride. Go with what is on the door.

Yep, that and when not towing drop down to about 40, if left at 65 they will wear on the centers more.

It is not just weight carrying that the 'recommended' PSI listing
on the tire's sidewall and various documentation from the OEM

Weight rating is just one aspect of it and IMHO, it has to do with
keeping the tire's shape during all aspects of it's duties

Keeping its shape as in not folding or rolling over during a curve at
highway speeds

Keeping it within the temp range it is designed for. Both at the speed
rating and weight rating

Keeping the contact patch within spec's for acceleration, cornering
and braking

Keeping its ability to absorb shocks at max speed is another

As are *ALL* of the 'recommendations' for 'that' tire. On that, the
vehicle door label is specific only for 'that' tire listed on that
label. Those who re-engineer by changing the class and size of the
tire needs to know what they are doing. Ditto the rim width vs the
tire OEM's 'recommendation' for that tire...etc, etc

The vehicle maker is giving you the pressure to meet their recommendations for weight rating, fuel economy and ride comfort. The tire maker is telling you what the tire maximum is and certifying they can carry the maximum weight rating they have established at that pressure. Unless you know how much weight is on each tire you will have to choose from the two.