ps0303

Purchased a used Chevy Express 2500 back in Dec. Been driving it ever since. Decided it was time to get the alignment fixed, oil change and tire rotation. The rotated the front tires to the back and back to the front. Did the alignment. Things seemed great as when I drove it home about 3 miles down the road no issues. Next day time to go do some work. Get on the highway and the van is shaking. Seems like front tires are not balanced. Go back to tire place, they say yes the tires are out of balance. They balance the front tires re install them and once again all seems good. Today, rear of van seems to be shaking. Then the "Service Stabilitrak" message comes up on the dash with the light. So after I get done doing what I need to do I head back to tire place. I tell the guy what happened. He grabs a tape measure and measures the height of the two rear tires of which used to be on the front. He says that one tire is 3/8" taller than the other one and that is probably why I am getting that message. The system thinks a tire is slipping and it is trying to compensate for it. Maybe I think. So I am wondering, is this true? Granted of which I never noticed, one tire, the taller one, is a different brand than the other three. Is that tire the problem as it is supposedly 3/8" bigger OR is the shake and the stabilitrak message do to the fact that tires on the rear are not balanced?

So before I go and just invest in two new rear tires, is it the balancing issue or the odd ball tire causing my issue? Pretty sure the shake is the tires not being balanced but will balancing them have any affect on the stabilitrak?

Thanks.

StanVan

3/8" is huge, in measuring by height. Left and right tires must be the same size, and a difference in brand or mileage will do some damage. I speak not from experience with Stabilitrak, but experience with All Wheel Drive. Your shake is probably wheel hopping. Invest in the tires.

ps0303

Thanks StanVan for the reply. I just wanted to make sure I wasn't being steered in the wrong direction but an overzealous tire salesman. I guess this would have shown up sooner or later.

mountainmanjoe

If you want to make sure he's being honest, then measure them yourself. In fact, if you want to be more precise, you can measure the circumference.

Yes, a difference in tire size will trigger warnings because the wheel speed sensors are not agreeing. To the computer, it looks like the bigger ones is turning slower while going straight which shouldn't happen. Your 2500 cannot be AWD, so no worries about damage. However, be aware that your ABS could malfunction because it relies on the same sensors.

Since all the wheels need to be able to turn at different rates, you are not getting wheel hop as Stan says. Just get a new pair of tires and see if the shake goes away.

ps0303

Dropped it off at Firestone for two new tires. This guy showed me something else on the oddball tire where it looked deformed on the tread. The other guy didn't catch that or go far enough into looking at it to catch it. Would have been nice if they saw it when they rotated them.