Got a turbo 2 and i needed to get new tires yesterday i guess I did too many burnouts a since my last set of tires only lasted 1000 miles, but this time I got used tires and they are both 235 45 17, one tire has like 90% tread and the other is like 60%, different brand tires too, would the difference in the tread wear out my diff , it's a 88 t2 74k miles

 

no, but the burnouts probably aren't doing it any favors.

 

+1 to the burnouts. Diffs will last through many sets of tyres on normal driving...

 

Can't imagine a great difference, but because of 2 different manufacturers, what is the difference in diameter?

 

If your S4 LSD has never been touched, as installed at the factory, then the clutches are already so warn that it will not be an issue, because it would be like you are constantly making a slight turn on a curvy road.

Now if you recently had the clutches redone in your LSD and they were setup fairly tight with say a more aggressive clutch lining material, then yes it could cause a premature rate of wear issue. If you had swapped in a Torsen LSD unit, then yes it would also be an issue. But this would be less of an issue if you had a S5 viscous LSD.

 

Burnouts kill diffs. Different tires can also increase wear. Even if both tires are the same size, in your case 235/45R17, they can still be different diameters. It also hurts that they are different wear rates. I hate percentages when it comes to wear. It's too subjective. How many in ?/32" is needed.

I just looked on tire rack and the overall diameter of 235/45R17 tires is between 25.2" and 25.4". Almost a quarter inch difference new, plus wear on old tires will change the number of rotations per mile, so yes, it can kill your diff.