So, while waiting for a very slow gas pump, I happened to glance at my doorjam tire sticker. Never bothered to look in the past as I know 3/4 ton trucks have E rated tires that run at 80 lbs. I was baffled to find it said I should have 65 lbs of pressure in all my tires. I have the 20" tire and wheel package but of course with a 250, they are still load range E which are always, in my experience, run at 80 lbs. Load range D tires found on half tons are generally 65 lbs. Anyways, has anyone else come across this? I will continue to run 80 in the summer when hauling my very heavy TT, but was thinking of dropping to 65 in the winter when traveling light to get a better ride. I just can't fathom a 3/4 ton truck running 65 and still being rated at it's max capacity. Anyone else with the 20" package notice this as well?

 

My old 37" Toyo M/T's were E rated tires with a 65psi max fill rating. Different tire mfg's have different requirements.

You should fill the tires to whatever is specified on the side of the tire, not the truck. Running a 65psi rated tire at 80psi is going to do nothing for your but cause premature wear. My current Michelin's have a max psi of 80 but I'm running them at like 62-63psi, close to the threshold before the TPMS light kicks on.

 

Agreed go by your tire manufacture not the door jam. My Procomps are rated to 65psi on the 18" and 20" both E rated.

 

Yes, the tires are rated at 80 and that's where I've been running them. To me, it just makes no sense that Ford is saying to run them at 65 on this truck. Well, we'll see if the sticker is a misprint when I drop them to 65 for the winter. If Ford is saying 65 then the TPMS must be set around 65. If it goes off at 65 then the sticker must be wrong and they should be at 80. Personally I ALWAYS go by the sticker. The max pressure on the tire is just that, the MAX in any application. Not so much on truck tires, but on car tires you will often find that different cars using the same tire call for different pressure to suite the application. In my case, I just can't fathom 65 lbs being the correct number for my application....

 

Huh? I guess you just never noticed. The tire sidewall rating is the maximum pressure rating, cold, when loaded to the maximum sidewall load. You cannot load your truck that heavy without exceeding the GVWR.

Your truck was shipped with tires that had a load capacity higher than the truck GVWR. Which is a good thing. This is why we have tire pressure load charts. The tire pressure that Ford printed on the label is correct when you have loaded the truck to its GVWR.

If you run the tires at 80PSI, you will enjoy a rougher ride and possibly wear out the center tread early. You might also enjoy a little better fuel mileage.

 

Sounds right to me. So, my plan stays the same. In the summer I will run them at 80 to deal with my trailer and quad combo that need all it can get. In the winter, it's down to 65. Thanks!

 

My sticker calls for 75 front and rear. The factory recommendation is what the engineers determined is the proper inflation for stock tires for the best ride, handling and tire wear. The PSI rating on the tire sidewall is just the maximum PSI rating for the tire.

 

My sticker says 50 in the front and 80 in the back. My tires are rated for 80 psi cold and i run them at 55-60 all year round

 

this is the truth

the manufacturer figures out the ideal characteristics that are affected by tire pressure, and tells you how to inflate your tires.
the sidewall is only the maximum allowed by THAT SPECIFIC TIRE

lets look at an extreme example

the corvair, when it first came out had a real problem with oversteer
chevy figured that if they decresased the front tire pressure, the increased slip angle of the front tires would equal out with the rear's tendancy to oversteer (due to the excess weight and poor suspension) and you would be left with a car with neutral handling.

IIRC, they decided to inflate the rear tires to the normal 35 psi and inflate the front tires to 17 psi or something like that

the problem happened when an owner decided to inflate the front to 35 as well and encountered massive oversteer as a result

the same is true with my truck.
my rears are set a 80 and the fronts are set at 50
this is the manufacturer's suggestion
the reason is that the lower pressure up front will give you a more wishy washy instantaneous turn in response... in other words, there is less of a tendancy to oversteer with a sudden steering input.

the higher rear pressure still allows you have maximum capacity from the tires

the second you install new tires that are a different tire than the one the truck was sold with, you have to figure this all out again on your own.
even a different tread pattern (or rubber batch) will change the ideal tire pressures.

in my case, i run 75 up front, and 60 in the back.
i find that the higher pressure up front allows me to get away with a poor alignment and still get even tire wear
the 60 out back gives me a softer ride, and since the rear tire wear is not much affected by tire pressure, then i go as low as possible without wearing the edges of the tires out prematurely.

its a balancing act.

 

I agree with the last few posts. It's always what I've thought was the case. I'm still surprised though, that 65 lbs is enough to get my tires to meet my GVWR. Every other 3/4 ton I've seen needed 80 lbs to do the same.

 

GVWR has nothing to do with it. That is just a made up number for vehicle classification purposes. It meant something in the old days but not any longer. Actually, the term "3/4 ton" or "1 ton" have gone by the wayside as well.

Assuming SRW...
Simply put, the psi listed on your door jamb sticker is the psi needed for two tires to handle the axle weight rating as listed on the same door jamb sticker (either for the front or rear axle). Of course this only applies while using the OE size tire. Change the tire size and the sticker info will be worthless.

For example, for LT265/75R16 E rated tires: 50 psi is required for that tire to handle about 2335 lbs each. 55 psi = 2600 lbs, 70 psi = 3042 lbs, 80 psi = 3415 lbs (which is the max number listed on the sidewall of that tire size).

The axle weight rating listed on the sticker is computer chosen on the assembly line based on the option packages ordered on an individual truck by truck basis. The computer chooses the spring code, which comes with an associated axle weight rating and the tire psi is then chosen from the tire pressure load chart (which is an industry agreed upon load chart for a given size tire in a given load range). The psi listed on the sticker will never exceed the max pressure listed on the sidewall of the OE size tire.

If you are loading your truck near or over the axle weight rating then running max psi (as listed on the tire sidewall) is a reasonable practice. There is nothing wrong with exceeding the psi listed on the door sticker as long as you are not exceeding the psi listed on the sidewall. Like previously mentioned..the potential drawbacks would be ride quality and tire wear.

 

I would not run the maximum pressure indicated on your tire unless you are carrying the maximum load specified on the tire. I have been told that is not a good thing to do as is running under pressure. Figure out how much weight you are carrying/towing and adjust the pressure accordingly. Contact the manufacturer of your tire and they will explain it clearly.

 

Yes, I know and agree with all of what you said. Hence what I wrote above. When at or over my GVWR I'm now at 80. During the off season, I'm at 65.

 

I misunderstood your original post. I thought you were saying you had E rated tires that had a max psi of 65, but you were running them at 80 because of the sticker on the door jamb. Sorry 'bout that.

I agree with what others have stated here.

 

on my OEM 20's I run 65psi all around unless I'm towing, or heavier payload in rear, then I'll pump em up to 80 (rear only). But thats not often.