do we follow the P.S.I rating on the tire or the inside of the door, here's the thing, I have had to put new tires on and they call for 2250 lbs at max 50 p.s.i. cold so I aired them to 45, the door label says front 35 p.s.i and back 40 p.s.i. I'm not used to having a truck this big, on my ranger i just kept it at 35 all the time.. thanks fella's

 

Defintely the door sticker.

The auto maker don't know what tires but, they know their vehicle.

The tire maker don't know what vehicle, they know the MAX psi for their tires.

 

I hate to contradict the Grand Poobah Smarty Pants...cause he will prolly open up some new words on me...but here goes :-)

You should go with the info on the tires. Just from the numbers you provided, i would say you have put "LT" tires on your truck. Every new Ford I have seen comes new with "P" tires, which run lower inflation. The sticker in the door jamb assumes you will always use the crappy sorry no good piece of junk tires that they, in their infinite wisdom, have fitted onto your F-150. And they have listed the inflation rate for those tires there in your door jamb. The tires they have put on your truck are not even good enough for a Crown Vic driven by a Grandma to the grocery store once a week, much less a full size, ground pounder like a F-150.

Now I'll 'splain what I just wrote. LT tires (Light Truck) have squarer shoulders, thicker sidewalls, have higher load capacities, and take higher inflation rates than "P" rated tires. Oh yeah, they usually cost a bit more too, depending on brand. They ride a little rougher too. That and cost are the two main reasons new trucks don't come with LT tires as they should.

"P" tires (passenger) ride smooth. give alot in curves, have low load rating, are cheaper, and use a lower inflation rate. Usually somewhere in the 30's (p.s.i.)

Example.....my truck came with GoodYear P265 70R17 (piece of crap tires)

I replaced them straight away with BFG LT265 70R17 (dadgummed great tire!) and I keep them inflated to 45 psi in the rear and 40 psi in the front.

 

RebelYell, I think I deserve partial credit.

The question was:

Door Sticker or Tire Marking.

Though the tire may use more than the number on the sticker, the ratio front/rear on the sticker is still valid and should be taken into consideration.
(even you do that)

There are people who would read "ignore the sticker, go with tire marking" as reason to pump them all up to 50 and complain about the handling and the creaks and rattles the truck has.

They might also complain about the bone-jarring ride, hmmm..."RebelYell"....

 

Sounds like you have LT, 6ply, load C rated tires, 50 psi cold max. When you have the truck loaded up, pump the tires up to 50 psi. When you are running empty, experiment on what works for you and the the tires you have. You should be aware of ride comfort, handling, and tire road noise, because each will change with the tire pressure. 44psi front, 40 psi rear might be a good place to start.

What is listed on the door jam is for a stock P rated tire. Once you deviate from the stock P tire, you should always follow what is on the tire for max/min pressure. But YOU must adjust the tire pressure to your own driving preference and load on your truck.

 

My truck came w/ LT 265/70/17 Goodyear AT/S - the door jam says 35 PSI cold front and rear. I just replaced them with Hoosier DTs(?) - same thing as Big Os tire - and they were sitting more on the center of the tire than on the entire ground patch area at 35 PSI. I deflated the fronts to 34 and rear to 32.5 and it seems about right. If the Hoosiers have over 35 PSI, the truck seems to bounce down the road.

It depends on the tire AND the vehicle. The manufacturer sets the pressure for the vehicle w/ the stock tire. Once you change tires, you may need to change the pressure from the vehicle's specs. The tire only gives max PSI and load ratings, not recomendations for everyday driving.

 

All very good points made here. (Even Raoul!) j/k.....

Just like to confirm what's already been said. You only need to go to the MAX COLD psi, when you are hauling/towing. When running around empty, it's going to really depend on what you feel is comfortable for everyday driving.

This is just what I do, but works for me.

When empty, I keep the rear at 40 and the front at 44. This is actually opposite of what the door sticker recommends for the actual "ratio". My sticker says 29 front, 32 rear...

Like I said, this just works for me. I really like the way it handles. Not "musshy" at all on the front and the rear end is not so "harsh" either. I carry one of those cheap air pumps and when I need to "pump up", it's a pretty simple process.

I think the sticker has these pressures because they have to take into account the stock tires they provided and those people who would not think about weight and load ranges. One day they will be taking the kids to soccer practice and the next day droping a yard of bark mulch into the bed. Now, they have the rears at the "loaded" psi to start with, so the user don't have to think about it.........

 

Follow the tire markings!!

The tire markings tell you what is good for that particular tire... vehicle independent, could be mounted on a Ford or a Chevy or WHY.

I run my 275 AT/S Goodyears at 37/38 and not 35. Better gas mileage and still below the 45 max rating. Any more and the ride gets to firm.

If you bought LT tires which go 50psi or higher then you would never want to put 35psi in them especially with a camper or heavy load in the back, otherwise it feels like they want to squirm off the rim around corners.

You have no warrantee from the tire manufacturer if you over or under inflate so follow tire sidewall recommendations.

Door stickers are usually only useful for the original OE tires.