I mounted some tires to use as a burners to do some sliding so I don't burn my dailyes the car is a 93 Miata which is a RWD. The tires I mounted on the back are both from a civic but the tire size is different, it is something like 185/70/14 while the ones that were on the back and are also currently on the front are 160/50/15 or something like that not quite sure. My question is as long as the tread depth, the wheel and tires are identical am I risking any damage to my differential?

  • do you mean different sizes front / rear or rear left / right?
    – Solar Mike
    Commented Apr 11, 2017 at 4:59
  • Please check the tyre sizes, there is no way a /14 tyre and a /15 tyre would be interchangeable because the wheels would be physically different. Commented Apr 11, 2017 at 8:07
  • My mistake @SolarMike and Steve I meant wheels with tires on them
    – method
    Commented Apr 11, 2017 at 20:54

1 Answer 1


No you should be ok with different sizes on the rear compared to the front.

Having each side the same is better for your diff. Especially for normal driving where you have traction on both wheels as the diff is constantly working to compensate for different rotational speeds.

However, doing burnouts and drifts is hard on your drive train anyway. If youre doing that with both wheels spinning then having different sizes would make little or no difference.

The most extreme workload for your diff is having one wheel with traction and the other spinning. In this case the tyre size would be irrelevant.

Having equal tyre sizes is most important on an all wheel drive car. Where it has front, rear and centre diffs.

  • A differential is made to enable different rotation speeds between left and right tire. Normally, those differences are caused by cornering. Having different tire sizes L/R has the same effect: the pinions have to spin a bit to compensate. This will cause wear of the planetary gears, but those should be able to handle this for years. The wear items in a differential are the pinion and ring gear, those have to rotate all the time and they absorb the full torque of the engine. The forces on the planetary gears are much smaller.
    – Hobbes
    Commented Apr 11, 2017 at 8:50
  • I think the miata may have some sort of LSD
    – r.anderson
    Commented Apr 11, 2017 at 9:21
  • I don't think so, the first LSD was on a 1999 limited edition (en.wikipedia.org/wiki/Mazda_MX-5).
    – Hobbes
    Commented Apr 11, 2017 at 11:39
  • @Hobbes well from 90 to 3 they have VLSD which after time and wear turns into open diff
    – method
    Commented Apr 11, 2017 at 20:55

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