Mismatched Tires and differential wear?

[apalt]

Greetings. Looking for some opinions or cautionary tales of running full time with a tire that is 2/32 bigger than the rest. Will it damage the differential over time or cause alignment issues? Just curious what you guys think.

Here is the back story. I run boring Michelin Defender LTX tires on the stock rims. I developed a really slow leak in one of them, so I took it in for rotate and balance and told them about the leak. They found a very very small piece of metal in the sidewall, so not repairable. Tires are all at 8/32 and new they are 10/32. I am considering putting the spare on which was purchased at the same time as the other 4, so it is brand new, but it is slightly bigger (2/32) having not been used.

 

[Mike NXP]

Others may have a different opinion but mine would be that's just fine to do. Maybe on a sports car or something with tighter tolerances but on a big AWD SUV like the 100 series I don't believe 2/32 will make a difference.

Will tire shop mount the spare or will they say its too far off and try to make you buy all 4?

I see you are in Alaska, are you highway driving a lot or more rural routes?

OR

How bad is the slow leak? Topping off air every day?

 

[apalt]

The leak is about 3 psi per week. I'm able to monitor and stay on top of it. Tire shop is more than happy to use the spare, and in fact think it's just fine and don't want me to buy 4 new ones. Nearly all of my driving is on paved roads.

 

[Mike NXP]

The leak is about 3 psi per week. I'm able to monitor and stay on top of it. Tire shop is more than happy to use the spare, and in fact think it's just fine and don't want me to buy 4 new ones. Nearly all of my driving is on paved roads.

Shoot I guess I just don't know enough to say for sure but I can't imagine its a big deal.. do some searching around on Mud to see if others have had problems relating to it...

what kind of mpgs do you get with those tires? Ive been moving more away from off road tires, they seem to do more bad than good for most of what I do. I've got highway tires on my 470 and it can still climb a rocky trail with ease

 

[William839]

Will overheat the spider gears if the difference is too big

 

[OEMGUY0720]

You should be good theoretically and in reality supporting the principle of gear backlash tolerance.

 

[Norilsk]

You'll be fine. One time I had one of my 37s explode on the road (didn't bring a spare 5th 37, duh), so I drove over 180 miles on a stock tire at the rear with my stock 4:30 gears and ARB locker — just stay under 60. It still drove fine, nothing exploded, no shavings even. I did an oil drain afterward since I had to reseal the ARB locker anyway, everything looked good on the inside, coper line was incorrectly routed, but that was me DIYing.

 

[vipergrhd]

You'll be fine, don't worry about it. I work for a fleet and we have a lot of AWD and full time 4WD vehicles, I did a little bit of reading on this subject and from what I read is you can have as much as 4/32 difference and get away with it the main thing is that you rotate the tires regularly so it doesn't cause unnecessary wear on the gears. We measure tread depth every service and even then not all tires will have the same measurements so we have a rule that anything more than 3/32 depth we just replace all tires.

 

[Mark W]

I'm on the "it'll be fine" boat. 3psi a week is "Nuthin". Air it up weekly (about 5 seconds time to add that much) and continue with your normal day to day routine. Some sort of tire slime is worth considering too. That should easily stop that amount of leakage. *IF* the damage is up very very close to the bead, it may not get enough slime to that point to do that job. But otherwise...

Your next tire change over might see an irritated tire tech... but just how high does that rate in your life priorities? Give him a heads up that the job might be a little messier than normal... pay the extra $5 if that is how they do it... and drive on.

Also, that difference in "tire Size" between you unused spare and the "used a bit" other tires is irrelevant.

And... even the straightest areas of any of the highways up here... including the Glenn and the Parks of course are not gonna be long enough to put you in a situation that any tiny amount of spider gear action will even be a blip on the radar compared to the normal "working" the gears are doing with any little change of direction. Any time "in town" simply is not gonna be a factor so far as caring about tiny tire size differences.

BTW, a quick and dirty check tells me that the 2/32 difference creates a theoretical difference in tire circumference of about... 0.2% NOT 2%, 0.2%

nothing nothing nothing!

Mark...

 

[apalt]

Thanks for the responses. Mark W's comments about the math forced me to break out my slide rule. The circumference difference is actually .39 inches...so almost half an inch. So for every rotation one tire is going to be ahead (or behind) by that much. My gut tells me no problem for 100 miles or so, but if I do this for 25,000 miles it is going to tear up the rear differential and transfer case. Thoughts?