must all 4 tires be replaced at same time?
 

Hi,
My brother has a Blazer (2000 model year I think) with 4 tires with lots of tread left on them, but one got the side wall ruined.

He has been told he must buy 4 new tires rather than just replace the one, or else his transfer case will be ruined. Is this true? I understand this varies between different vehicle brands and models, and he cannot afford to do this if it is not strictly necessary.

It is an "automatic" type 4WD (i.e., you don't have to manually lock the front hubs).

Any help would be much appreciated!

Dave

I've done it in 2s when I had a 2wd. But I always try to change all 4. I dont trust all season, so its summers and winters. I've had different brands and different tires on, and it doesnt handle the same. Either match the 2 fronts and 2 backs, or match all 4 I say.

Size needs to match.

As long as the size matches, I think it'll be fine. Both front and rear diffs are open, so I seriously doubt the fraction of an inch difference in size from wear will be enough to damage anything

I try to match at least two fronts or rears like stated. From what I've read the AWD models have to have matching but that shouldn't concern you since it's a Blazer unless it had a conversion done which I doubt.

As mentioned, just match the size.

If getting a different brand, try to put the new mismatch on the front and keep the rears matching if it has an auto locking G80 rear end. If there's a slight tire size difference it can cause the locker to engage in slippery conditions when you don't want it to (taking off in the rain or snow, etc.). I ran into this with an old work truck, a Tahoe, and it was really throwing me for a loop for a while until I figured out what was going on lol. The rear end would lock up under hard acceleration when one tire would slip and the locker would engage, the truck would pull to one side like a tire was suddenly flat and would continue to do so until I either stopped and backed up for a foot or made a sharp right turn to free up the locked rear end.

This!

If you have the 4 button system with the auto feature , different size tires will be detected as wheel slippage and the T-Case will try to compensate for this and the clutches will wear out prematurely..... 3 button system would not be a big deal .

This would only be the case when using the Auto4wd mode. In 2HI the viscous clutch is disengaged. In 4HI, it is fully applied (no slip).