I found a bubble in my front right tire's sidewall on my 2006 Mazda3 2.3L (FWD, open diff). So it needs to be replaced. The replacement tire will end up going on the rear as it's time to rotate them anyway. Will any damage be done by putting the new tire back on the drives in 5,000 miles after the next rotation?

Specifically: Am I going to damage the diff by putting tires with a 20,000 mile wear difference on?

  • if there is a bubble in the sidewall, the tire has a defect in manufacture and it should be replace IMMEDIATELY. The tire can blow out without warning. I believe most tire shops will prorate a replacement of the tire since this is almost always a manufacturing defect and not a result of driving habits.
    – Patrick
    Commented May 30, 2011 at 15:22
  • Yeah, I got it replaced, along with the tire on the other side. I asked the tire guy about warranty replacement and he said the exact opposite, that if the tire has been good for awhile and suddenly bubbles then it's likely a pothole or damage, while if a tire came from the factory bubbled or bubbled soon after it'd likely be a manufacturing defect.
    – Parker
    Commented May 31, 2011 at 11:59
  • 1
    Just to be on the record here, sidewall bubbles can also be the result of driving on an under-inflated tire, which causes undue sidewall flex and heat buildup, which can cause the separation/delamination that forms the bubble. Check tire pressures often!
    – mac
    Commented Dec 6, 2013 at 17:06

2 Answers 2


Not sure what damage might happen to the diff, but on the front axle this might cause the car to pull one direction or at least create extra stress due to one wheel gripping differently than the other side.

I would suggest replacing the tires in pairs. Although if you only had a couple thousand miles wear, then it might not be a big deal.


I'd say 20k difference for tires is a lot. Generally the recommendation is to keep the tires paired (2 fronts and 2 rears) at even wear level. For your car it'll most effect handling because left/right will have different grip.

As far as the diff, you won't do any damage at all. You have open diff, which means there's no clutch plates, or gears that would be constantly ground because of slightly different tire diameter. If you had limited slip diff, you'd have to be more concerned as different tires not only put constant load on the diff itself, but also on the drive axles.

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