So, I am getting close to needing new tires on my 2001 Tahoe 4X4. I was looking at my tires today, and discovered that one tire is a different size than the rest! 3 tires are 265/70R16'S, and my left rear tire is a 265/75R16. They are all the same tire with similar tread wear. Anyway, any thoughts on if this could casue any damage to the rear-end? Thanks again!

 

If my calculations are right, the 75 tire has ~1" larger diameter. Thats enuf to cause your differential to be engaged all of the time when going in a straight line. If you have Stabilitrak, I'd think that it would be tripping a message or code. I would want to get that LR replaced. If the other three still have quite a few miles left, you might consider getting a used tire that's close to the same tread depth as the other three. I've had pretty good luck w/ used tires. Got lots of experience when the kids were just starting out.