Tires: tires, tire dealer, tread pattern

Question
I have 4 Bridgestone Dualler AT P265/70R17 tires, one tire is a slightly different tread design. The tire dealer says it is fine, that it is a replacement for an obsolete tire. If I measeure the circumference, there is about 1/2" difference. How much should I be concerned with before possible problems with drivetrain?

Answer
Carl,

This is more of a vehicle issue:  How much can the drivetrain tolerate?

But I'm guessing the tire with the different tread pattern is the smaller diameter.  You should be aware that tires grow in service, so would expect a new tire to be smaller in diameter.

I would suggest that you put this tire on the front and about 5,000 miles from now rotate ir to the rear.  It should have finished most of its growth by then.

BTW, it is always best to replace tires in pairs to prevent this sort of issue from becoming a problem.