I have a set of Dunlop load range E tires on my F150, the recommended air pressure stated on the sidewall is 80 psi cold. I've never had tires that required such high pressure. Well, the outfit that installed them only inflated to 50 psi cold, and I've since put at least 20K on the truck.

You'd think that if they truly were under inflated, the edges would be worn, but I have just the opposite. The outer edges are practically new, and the center section is completely worn. The center inch or so is completely smooth, and it tapers up to practically new looking tread over another inch on either side.

I just pumped them up to 65 psi cold. Im afraid to go any higher for fear of a rim or valve stem letting go. Does anyone else keep their tires at 80 psi?

 

50 is about right for a LR E tire. The 80 is the maximum pressure, not recommended pressure. Can't say why at 50 it would wear that way as that pressure should be about the proper inflation. I ran a set of BFG ATs at that pressure for 40k and still had tread on them when I traded the vehicle. Most LR E tires handle about 3000 lbs at max pressure. As the axle of an F150 is rated at under 4k, 50 psi would give you about 2k per tire. Which would be about right for any load you would carry and still keep it within the trucks rating.

 

So you've never heard of an under inflated tire with the center wear... The strange thing is when I placed a straightedge across the tire tread, there was a gap at the center of the tread. It would seem that only the outer edges are in contact with the road surface, yet the center shows the wear. So could it be the fact that I drive like an a**hole that makes the center of the tire bulge out? Hard cornering at high speeds on the parkway, perhaps?

Most of the mileage is highway, and here on Long Island we all drive like psychopaths.

 

Are your dunlops mud rovers? I have heard alot of mud rover owners complain about uneven wear and tires going out of round.

 

who 80 is the max air pressure you can set them at but inflate them to what your owners manual says should be somewhere around 35 or so (i think) Mine said 65 max and i threw a flag to but when i called the place they said inflate to what the manual says and i have no idea about the wear pattern

 

To me it sounds like they are over inflated if it had wear on the center of the tire, but you mentioned underinflated..confusing. My dad had the same kind of wear on an old set ot directional tires that were on the truck when he bought. They had almost not tread in the center but tons on the edges, he said they must have been overinflated and driven a long time.

 

Your tires are way overinflated. Load range E tires are common on 3/4 ton and 1 ton trucks and with the weight that one of those trucks carry it is necessary for the sidewalls to be stiff. A Load range E tire on a 1/2 ton shouldnt need over 35psi unless you are overloaded.

 

35 is way too low. You are well below the rating of your vehicles weights at 35. Think about it. LR E tires can handle approx 3k at 80 psi. At 35 you are below 50% of max. Less than 1500lbs per tire. Your truck is rated at 4k per axle.
An under-inflated tire is just as dangerous or more so than an overinflated. Under-inflation causes heat, which causes tread separation and blow-outs.
The 35 psi in you manual or on the door sticker is for vehicles originally equipped with P series tires. Those that came with LT LR C tires have a recommended pressure of 40.

I have found in the past with tread wear that they following pressures work quite well.

P series tire max of 35, use 35.
LT Tire LR C max of 50, use 40.
LT Tire LR D max of 65, use 45.
LT Tire LR E max of 80, use 50.
These are for use on an F150, not a SD. Pressures for a SD would be higher.

Who?. tread wear in the middle is always over-inflation.

 

I would guess his 1999 weighs less than 5,000 lbs.
My 1999 5.4L regular cab weighs 4,200 lbs
Further, since he mentioned highway miles I would guess the bed is empty.

50 psi was over inflated causing the uneven wear.
65 psi was definetely the wrong way to go.

If 35 psi looks too low, try 40 and consider it a lesson learned.

 

Actually I used 50 on a 98 reg cab with 5.4. As I mentioned, at 40k the tires were still good.

In fact, if the vehicle had OE tires that were LR E, and had a TPMS system, it would be set to go off at 46psi.

Look at the chart they have at this site, about 1/4 of the way down.

http://www.nhtsa.dot.gov/cars/rules/...ule.html?name=

 

Well, it could be as simple as a faulty gauge.
50 worked for you and he has middle wear at 50.

 

Which could also say a lot about the tires.

 

Not to highjack this thread but

I just put some Toyo AT's on that say they are load D but the max inflation only says 50psi, which is kinda odd since usually load D is higher around 65psi.
The tire place put any where between 34-38 psi in the tires. Do you think this is about right?

Thanks

 

They have started making some LR D at 50 and LR E at 65. I would try those at around 40 all the way around and keep an eye for unusual wear. 34 definitely sounds a bit low except for an unloaded rear.
I would not go any lower than 37-38.

 

Hey guys...

Sorry it took awhile to get back here, work got real busy.

So someone mentioned that center wear is ALWAYS over-inflation. That's what I always thought as well, but I was just confused by the pressure rating on the sidewall... I didnt think it was only a max allowable rating. I dont see how Fords recommendation on the doorpost should be followed when using non-OEM tires. Thanks Kingfish for posting the chart.

I'm still a bit lost, because I rounded up the tire pressure in my first post to 50.. They all varied between 43-48... So I was below the recommended pressure for an E tire, yet still had the drastic center wear. I will drop the pressure back down, since the 65psi I put in will only make it worse.

The truck sees different loads all the time. The truck weighs in at 5240, and any given day I could have either nothing in the bed, 500 lbs of concrete, 700 lbs of sheetrock, or a couple hundred lbs of tongue weight from my overloaded 5x8 work trailer. I suppose I'm running empty 60% of the time though.

Any other thoughts appreciated.