An inattentive driver turned in front of me 2 weeks ago and I hit her with the right front quarter panel. Pushed my bumper into my sidewall and blew out the tire. She was cited and drove away, my tire was trashed.

The current set of tires had maybe 20,000 miles on them. Still lots of tread depth left, but certainly not "new".

The insurance company of the lady who pulled in front of me paid for one new tire and it was mounted on the front right wheel.

Truck is 4wd.

Upon speaking to the auto-body guys, they said do NOT put that new tire on the rear because being a slightly different circumference from not being worn down, it would "burn out" my rear differential.

But they said it was OK to leave it on the front. Anyone have any feedback on this?

If I can't put that tire on the rear, I won't be able to rotate my tires.

Will I have any issues using 4wd in snowstorms going down the highway with a tire on one side that is slightly larger due to less treadwear than the other?

 

Haha, that's ridiculous and hilarious. I guess the same way some people believe you shouldn't run your headlights at night because it'll give you bad gas mileage (no such thing as free energy, after all!) or other silly things. Apparently he doesn't know how differentials work.

 

My truck has limited slip differentials, I called a second dealer who agreed that it "could" be a problem because it would stress the differential since its not an "open" differential.

Here is an article that seems to corroborate his concern.

Tire Tech Information - Matching Tires on Four-Wheel Drive and All-Wheel Drive Vehicles

 

So why don't you buy your tire from Tire Rack and get them to shave the tire like what is mentioned in the bottom of this article?

 

2 reasons... First because the autobody shop had already acquired, mounted, and balanced one new tire. It was already on the truck.

Second, the tire rack doesn't sell the tires I have on the truck now.

As I've worked this over all afternoon, spoke to 2 dealers who researched it.

If anyone was wondering there is some guideline from Ford that states that if a tire has more than 10,000 miles on it you should replace both on the same axle.

Based on that, the insurance company is going to pay for another new tire and then just take off a "betterment" charge on the tire. So each axle will have matching tread depth on the tires.

There is still a bit of added stress on the transfer case when in 4 wheel drive due to the different circumference on the front vs. the rear, but since I don't drive around in 4wheel drive all day every day the additional stress on the transfer case would be negligible.

 

You're not going to hurt a thing, there are lots of rumors flying around here.

A slightly larger circumference is going to cause them to rotate at different RPMs for a given speed. But the whole purpose for a differential to exist is to permit each weel to rotate at different speeds. Limited slip differentials have clutch packs that engage when there is a high speed differential. The minute speed difference that would be caused by different size tires isn't going to cause problems.

 

Yes, what Crazy001 said, which is basically what I said.

OK, no, please stop thinking along these lines as well. First of all, you should not have 4WD engaged on a high-traction surface, including wet pavement (as compared to dirt or a layer of snow/ice). There's no slippage in the transfer case. Your tires may or may not be microns different, but the gear ratios in front and rear are rarely EXACTLY the same anyway. Ever wonder why some people refer to them as 4.10's while some refer to them as 4.11's? You may have one in the front and the other in the rear. The difference is minimal, but if you keep driving on the street that way, it will begin to bind up. Some people who've done this with manually operated transfer cases may notice that it is a giant pain to get it out of gear again, even after putting it in neutral or reversing a little. If you keep it up long enough, you'll eventually break things.

So will that 1/64th of an inch of difference in tread depth really matter? What about if one tire has a few pounds less air in it? Ever notice someone who was visibly running different pressures on one side of an axle versus the other? The difference in tire diameter is much greater in that instance than any difference in tread depth. Do their axles explode? No.

Ford recommending changing tires after an arbitrary number of miles is a) some lawyer's way of justifying their own existence and b) a way to get people to buy more tires from their Ford dealership. 10,000 miles in a 5.4L standard cab that cruises around country roads empty is going to be massively different from a 6.7L Crew Cab long bed that transports 5 dudes from site to site at high speeds pulling a way overweight gooseneck behind it. And which tires with which compound? And even that difference won't really matter as far as your differential is concerned. There may be practical human-based reasons to do it, as people tend to forget over time that different tires may be more prone to failure or more worn down, etc, but it's not mechanical.

 

Depending on how old your spare tire is, it might
be worth moving the other front tire to the spare and buy the 2nd new tire.
Especially if your spare is the wrong size.
If you have a "new" but old spare of the correct
size/type maybe swap the spare and old front.

 

Lol some people are funny, did the autobody tech also tell you to replace your muffler bearings and check your blinker fluid

hopefully body work is all he does..

 

I would not run different size tires L/R, when you turn the smaller tire turns faster then the larger tire making it feel a little funky and there will be traction differences IMO. Well it mattered a lot in my little rx7 but not sure about these big trucks but why not try pushing insurance for 2 tires, never hurts to try, I just got $1550 of accessories for my car because the dealer stripped some threads in my bed box. Just explain to them what the techs said about being a safety issue. It won't kill your differential

 

All of your tires have a slightly different circumference. Even when new.

 

My old 95 F350 Plow truck used to eat front tires almost every year. Since I only really used it in the winter I had a friend who worked at a salvage yard, free tires for me! He waited till he had two with good tread and id throw them on the truck. I ran it hard for years like that with mismatched tires and never had any issues. By that theory you should never rotate your tires since the drivers side wears faster!

 

Any time that you drive in a direction other than straight forward or reverse, all four wheels are turning at different rpms. How would less than 1/4" make a difference?

 

ruschejj, I assume your question is rhetorical, but just to make sure there's no confusion at all: it doesn't make a difference. It's just the kind of ignorance that spreads from person to person, where no one really knows what they're talking about enough to realize it's ridiculous, so it just keeps propagating. Kind of like people thinking putting action-movie accessories on a Mini 14 or spray-painting it black makes it any more more or less deadly and takes it from a "ranch gun" to an "assault weapon" (reminder: neither term has any real meaning), etc, as part of the current swirling crapstorm of self-righteous ignorance and angry fear we're dealing with right now.