I have a 2001 Chevy Astro van with 110K miles. When going at a slow speed (10-15 mph) I notice a thumping in the rear at approximately 5 second intervals. A mechanic told me that AWD vehicles need to have all tires replaced at the same time and if you don’t it will ruin the drivetrain. He says that is my problem. Can anyone confirm that all tires on AWD vehicles need to be replaced at the same time? Thanks.
He is mostly correct. While a small difference in tread wear is acceptable, if your tires are greatly different in tread depth, this will affect your center differential and you will eventually wind up with mechanical problems. More than likely, this topic is covered in your Owner’s Manual.
Typically yes on AWD vehicles. The reason is that your tires if not same wear/model/make will turn at slightly different speeds causing slippage in part of the AWD called the center differential that distributes engine power between front/back axles. The center diff. is designed for slippage when you turn(esp sharly) since your wheels turn at different speeds even if perfectly matched. However running a vehicle in this state of slippage constantly ruins the center diff. and running different tires during a sharp turn basically it needs more slip than available which turns into thump thump.