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?
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.
