what tire pressures would you recommend in my truck with the stock 265/75/16 E tires, truck empty? Roy

 

I run 50 rear and 70 front.

 

CPS

your tires will tell you what the maximum tire pressure can be. do not exceed that pressure. also remember when you are driving, the heat created by the friction of the tires rolling on the street will raise the air pressure in your tires by about 3-5 lbs.

that being said, here's where I and most of the people set our pressure at.

my truck is a 99 f350 7.3 dually, my tires are rated for 80 p.s.i. max
I set all my tires at 75 p.s.i., it gives a little firmer ride, not bothersome, and helps the mileage a little.

the truck manufacturer lists what they say your tire pressure should be, it's listed on the tag in the door jamb.

I believe the way that they want you to set it is way too soft. and I think they do that just to improve the softness of the ride, but the handling will suffer. especially in cornering and load carrying.

good luck

John M T

 

This is very interesting about having 75 psi all around on a dually.
I, too have a LATE 1999 F350 2wd CC long bed dually that I put a brand new set of 6 Cooper 23585R16E (which are the factory size tire for my truck) recently, and started out with 80psi that the tires are rated for, I have dropped the rears down to 40psi just to get all the tread surface on the ground on the rear-with 80psi I had about 2" in the center of each tire on the ground, I run empty 95% of the time, I have gone to the factory recomended 60psi in the fronts and the truck seems to handle pretty well.
I understand that the EARLY 1999 duallys has on the sticker that 45psi all around but have never seen this for myself, are the Cooper Discoverer HTs an extra hard 10 ply tire or is it my truck????
Also, I have had my front end alligned and everything was checked and new shocks were installed and still I am getting strange wear on the fronts-kind of hard to explain: first off I can look at my tires and see the irregular wear pattern, and I can feel it by rubbing my hand clockwise over the tread (towards the rear of the truck) it feels sharp, then is I rub towards the front they feel almost smooth, any ideas on this?? I know my tire dealer doesn't care about it because the worst thing that will happen according to him is that I'll have to buy more tires!!!!
Is it possible that they might be using the wrong specs??

 

I agree.. 75 psi will probably cause extra wear in the center on the rear.. I just checked my door sticker, and it says 60 front and 45 rear on my early 99 DRW..
I had funny wearing area towards the outer edges of my original Generals and i am sure it just the tire and how the belts are made at the factory.. Been running Michelins about 3 years now and they are wearing perfectly even.

 

I just read an artical yesterday on tire pressure and the jist of it was to split the difference between the door tag and the max pressure on the tire and here's why. The vehicle manufacture will have the tire pressure lower for better ride quality, at the expense of tire wear. The tire manufacture will list the pressure high for longer tire life...so split the difference and you get the best of both worlds...for example if the door says 70 and the tire say's 80, then 75 would be a happy medium

I hope that helps!

 

Thanks for the input guys. The reason i was asking is that the door jam sticker says 80psi rear,55psi front.The tires say 80psi max cold. i just thought that 80psi on the rear was a little much with only a canopy on. It seems like most of the weight is on the front with the engine over the wheels. My thinking was to have less air pressure in the rear for better traction and a better ride and more in the front for less rolling resistance and easier turning. The tires i have now seem to have more wear in the center of the tread indicating too much air. I have been running 70psi in the front and 65psi in the rear.Just a note to Supercab about his irregular wear on his tires when he runs his hand over the tread; that is caused by improper rotation or not rotating the tires soon enough.

 

CPS: My irregular tire wear showed up from brand new @ about 2k miles very slightly, then rotated side to side (fronts) and had allignment done, and now with about 2500 miles the tires are twice as bad with this irregular wear that they were before.

 

well, you could do this..

1. put the tires up to sidewall pressure
2. take a tire crayon and make a mark across the treads every 1/4 of a revolution
3. drive the truck a quarter mile or so
4. decrease air pressure in 5psi increments
5. and repeat steps 1-4 until the paint mark is wiped from the entire tread face

now that that's been said, Goodyear says not to run less than 15% of the maximum sidewall pressure in a tire... so for a tire with 80psi sidewall pressure, run no less than 68 psi

 

I believe we are talking about 2 different things here: 1 is the high air pressure on the rears of DRWs and the effect lowering the psi has in the center wear.

The other is my irregular wear pattern on my FRONT tires: I really don't think the psi is the problem here--I think its some kind of allignment problem--I've seen this kind of wear pattern before on other Ford pickups from F150s to F350s, there has got to be a comon denomanator here....I shouldn't have this kind of wear pattern after just 2k to 2500 miles of unloaded highway (non-off road) driving, I am going to take it back to my tire dealer and have them check the allignment again, I wonder if there was a change to the specs from EARLY 1999 to say a later 2000 and up model, and they are using the wrong specs to work from??

My LATE 1999 has only 78k ORIGINAL miles on it and no front suspension/steering components were found loose or warn out before the allignment was done.

 

When you rotated your tires i would assume that you put the rear tires(outside ones} on the front staying on the same side and the front tires are moved to the rear, right? If that does not help try what JLDicmon says in his post. Roy

 

Just read your latest post, I had the same issue with a 78 bronco and i had to rotate the tires a little more often and play around with tire pressures till i found what worked and my aligment was fine. Although tire rotation is a little different for a dually. Let us know what the shop says. Roy

 

Excuse my poor understanding of tire lingo, but it seems to me that braking will wear the front of "knobbies" down more than the back, knobbies being the raised portion of the tread separated by valleys (at least that's what we called them on motorcycles). Aggressive off-road and snow tires tend to have lots of knobbies and valleys laterally (from side to side) across the tire rather than the "rain" valleys which go around the tire's circumference . Also since most of the braking (I heard as much as 80%), is on the front tires, the front tires will show this wear much more than the rear. I had a 4X4 once that if I didn't rotate the tires to the opposite side of the truck every few thousand miles it would get real bad real quick. I could easily feel the problem by rubbing my hand around the tire in one direction (it would feel smooth) then the other (and it would feel rough with the edges of the knobbies catching my hand).

Another thought on high pressure on the back tires of my dually. My wife won't drive the dually in the rain cause it will slide out on her going around corners. Seems like my door panel says 60 lbs all the way around, and I have been running 70. The tires are rated at 80 max.