Tread wear outer dually tires on F350

[Bruce and Jenna]

Never seen this discussed before. I have 39,000 miles on my 07 F350 dually diesel Tow Boss. I'm the original owner. I've pulled a 15,000 pound fifth wheel for maybe 10,000 of those miles, keeping my weight 1,000 pounds below the truck GCWR.

I just checked the tires (Continental LT245/75R17all around). The middle of the tread of the outer dually tires are worn down, just about even with the wear bars. Inside tires look just fine, as well as the front tires.

I monitor my tires frequently, particularly since I have Pressure Pro sensors on all truck and trailer wheels. 75F/60R towing, 60F/45R not towing. I keep the same pressure on all four dually tires. Don’t drive hard anymore like I usta.

The outer tires wear pattern indicates overinflation. Should I have maintained lower pressure in the outer of the dually tires when towing of not? Or has someone been following me around with sandpaper, sanding down the middle tread, and he's too lazy to reach in to the inside tires?

Now I need to find two used LT245/75R17, so I don't need to replace four or even six tires.

Your thoughts??

[powerboatr]

sounds like overinflation
on my 06 tow boss i had the fronts broken down and put on the inner set ,
looked odd as they are bw and the fronts were rwl

i ran heavy as do you and never had more than 65 in the rears loaded
and empty i ran 35-40 to keep a flat tread wear pattern

[K-Star]

are you sure your inside tires are inflated to the same pressure as the outer tires? Sounds like you are astute enough to know that but have to ask anyway. It is not a good idea to run either tire with less tire pressure than the other.

[Bruce and Jenna]

Mr Boater,
Likely overinflation, but why only on the outer?

K-S,
Yes, I monitor my tires with my Pressure Pro sensors, confirmed with a digital pressure gauge. I keep all dually tires the same. And fronts at same pressure too. I could think that one of the rear sensors is wrong. But the wear pattern is the same left and right.

I was wondering if the outer tires wear differently in turns than the inner ones. But then this would be a common problem in DRW trucks.

I determined my unloaded pressures with the old chalk test, i.e. putting a stripe of chalk across each tire and looking at wear at different pressures. Loaded pressure I took from the tire manufacturer's label on tire pressures.

[wingnut60]

I put 95000 miles on my last 350, and got there on the original tires. The duals never showed odd wear. You could try moving the inners to the outer row, see what happens. Only other thing that might cause this--BOTH outer wheels are bad? Doesn't sound logical. Have you ever rotated the tires? Hard to do correctly because the wheels are polished on one side only--so I rotate front LtoR and rear LtoR only, to keep from having to break the beads.

[sknight]

Do you travel on interstates or stick to small twisty back roads?

[Bruce and Jenna]

I've never rotated the tires. Figure the cost of breaking them down wouldn't pay. Actually I've never rotated the tires on my cars either and usually worked out.

I seldom drive on gravel roads. Mostly good highways. Pretty conservative in my driving overall since I purchased this truck.

[sknight]

The reason I asked is because if you do a lot of turning the two tires beside each other get scrubbed a lot, at low speed the outer tire loses. That will greatly accelerate the wear patterns.

[Frankenstien]

Wingnut may be on to something. Might want to have some one watch your tires/wheels as you drive, if the wheels are bent it may cause an In Out push pull on the wheels.... basically causing them to go back and forth on the road as you drive. This would certainly cause the issue you describe.

[Ray,IN]

Usually the inner dual wears a smidge more than the outer due to road crown. What pressure are the duals? When towing our 15,500# GVW 5er(act. 14,700) I run duals at 65 psi. Since GM's rotate all 7 rims, and 4X4 is a "must rotate", I have Sam's club do it every 10K miles (part of purchase price).

[KC1BUD]

I own a 3/4 ton Chevy diesel, it came from the factory with 60 in the front and 80 in the back, but since I drive it more unloaded, the rear tires wore out just as discribed. Found that dropping the pressure from 80 to 60, the same as the front solved the problem. I would have thought that if this happened to be the case in a dually then all the rear tires should show excessive center tread wear.

[wingnut60]

Bruce,
Another thought--I had an '07 350 dually for 95400 miles on the original tires, and would have run them another 10-15000 if I hadn't traded. I always ran the rear at near max for the LR E tires, 75-80, due to high pin weight when towing. Being generally lazy, I never lowered the pressure for solo driving, even tho it was at least 85% of the time. You have a strange problem, hope you get it figured out.

[Bruce and Jenna]

Just talked with the Ford dealer. Who says that the outer dually tires will wear out faster if all are underinflated. I'm here to tell you there is a big difference in the inner and outer treads.

Live and learn (and spend). Guess I'll bump the unloaded pressure down to 40 on my new set.

Thanks all for your help.

[wingnut60]

I don't normally agree with Ford service advisors, but his answer seems to bear out that you run underinflated most of the time. 45psi on LR E tires isn't enough pressure. I run 75-80 loaded/unloaded and get great tire mileage.
Running at max recommended air pressure unloaded is NOT running overinflated--it just results in a harder ride. You should get max tire life and best fuel mileage when running at max recommended psi. Running at 90 on an 80 max tire is overinflated.
If you run at 40 on your next set, you will take a chance on the tire bulge at the pavement contact point rubbing, leading to a different set of problems.