Join Our Ford Truck Forum Today

Document your Ford truck project here and inspire others! Login/Register to view the site with fewer ads.

Tire PSI

MikeStoke

Army Firefighter
How much PSI should I run in my tires? The door sticker says 60 psi in The front, and 50 psi in the rear. The sticker behind the fuel fill door says 65 psi in the front and 55 psi in the rear. The tire salesman at Big O Tire said that the super dutys are so heavy in the front that they recommend 80 psi in the front and 65 psi in the rear on a dully inless you are hauling hevy loads, then fill to 80 psi in the rear. So What should I run in my tires? Thanks mike
 

MikeStoke

Army Firefighter
The tires are the correct sized tires for the truck, and they say 80 psi for single and dual. I just wanted to make sure, I didnt want to run to much pressure in them. Thanks Mike
 

Skandocious

Post Whores Make Me Sick
19,076
655
California
What Chris said. Don't fill it any higher than what the max psi on the TIRE says.

Actually I've got a related question. I've always filled my tires to what the max PSI says on the tire bu I was recently told not to fill all the way to the max and that it's supposed to be a MAX. Any truth to that?
 

Skandocious

Post Whores Make Me Sick
19,076
655
California
Well the reason they were saying that was because my tires bulge in the center and I was trying to figure out why. Of course the first thing they asked was if they were overfilled 'smiliedoh' Nope, I'm not stupid. Told them I had them filled to what the tires say. And they said that's MAX psi and to deflate them a bit until they stop bulging. I think it might also have something todo with my 12.5" tires in 8" wheels.
 

O'Rattlecan

Redneck Prognosticator
26,687
797
Belton, MO
I think you have your problem figured out, Chris. The tire is a little wide for the wheel. I too fill mine up to the max. If you decrease your tire pressure, you are going to have a very smooth ride though. Fuel mileage is more important to me though, so I just air those babies up.

Ryan
 

Skandocious

Post Whores Make Me Sick
19,076
655
California
I agree Ryan-- I'd rather have the extra mileage which is why I've always filled them to max... But I feel like if they're deflated just to the point where the tread lays flat on the ground (the way it's supposed to) then I shouldn't see a decrease in mileage right?
 

Skandocious

Post Whores Make Me Sick
19,076
655
California
thats what im kinda figuring. id think if its higher in the center it will where that part of the tread quicker. but idk im no genious.
That's exactly what it'll do, hence why it's not a good idea for my tires to be inflated to the point where they bulge. So I guess I'll need to play with the pressure until I can find the psi where it lays flat. Hmph.
 

O'Rattlecan

Redneck Prognosticator
26,687
797
Belton, MO
Well if you get down to the pysics of it, I figure the more round the tire is and the less tread that touches the pavement, the less rolling resistance and drag you're going to experience. If you're running around on basketballs, you're probably getting great mileage, but I'd be concerned with tread wear.

Ryan
 

Skandocious

Post Whores Make Me Sick
19,076
655
California
Well if you get down to the pysics of it, I figure the more round the tire is and the less tread that touches the pavement, the less rolling resistance and drag you're going to experience. If you're running around on basketballs, you're probably getting great mileage, but I'd be concerned with tread wear.

Ryan
But do realize that as you decrease the surface area of the tire that is contacting the ground, you are INCREASING the force that is being placed onto that surface. More surface area = more weight distribution. So I'm not entirely sure if your theory is correct.
 

O'Rattlecan

Redneck Prognosticator
26,687
797
Belton, MO
Yeah, the PSI of the contact area will go up. I think rolling resistance and contact area might be larger factors, but I'm no physicist. Either way I'd make sure my tread was making full contact like you intended anyway. :rofl:
That'll burn up a tire quick.

Ryan
 

Skandocious

Post Whores Make Me Sick
19,076
655
California
Yeah, the PSI of the contact area will go up. I think rolling resistance and contact area might be larger factors, but I'm no physicist. Either way I'd make sure my tread was making full contact like you intended anyway. :rofl:
That'll burn up a tire quick.

Ryan
Yeah I'm not going to worry about the physics too much-- just gonna try to make all the tread contact the ground and I should be in good shape.
 

6L PWR

Kansas Chapter member
But do realize that as you decrease the surface area of the tire that is contacting the ground, you are INCREASING the force that is being placed onto that surface. More surface area = more weight distribution. So I'm not entirely sure if your theory is correct.
AND you're decreasing your TRACTION for braking. There's a reason the manufacture's have the tire inflation pressures listed for a particular model and that's so that it has the right contact patch and doesn't cause wear on the middle or outside from over or underinflation as well as too much heat buildup that can cause catastrophic tire failure.

I have a 2006 F-250 Diesel and run 55 in front and 55 in back UNLESS I have a load in the rear and I up the rear to 80. That's on E load range tires too.
 

Truckin4life

Texas Chapter Leader
I run my tires at 10 psi...
I gave up on gas mileage ALONG time ago...
My truck rides like a caddy. Even at 50 mph, on a dirt road....
I might air them up to maybe 20 though...
They squat more than i like on turns....
 

Ford Truck Articles

Top