Tire replacement and differential problems

[Marvin C]

Will replacing one tire with a new tire of the same brand and model with the other three tires having 1/2 tread life left cause differential damage?

 

[bmart]

I would say yes, absolutely. They can shave the new tire to match. Another option is a used (exact make/model/size) tire from fleabay with the same tread depth. Cheaper. Easier. Been there.

 

[Dr. Mandrill Balanitis]

Will replacing one tire with a new tire of the same brand and model with the other three tires having 1/2 tread life left cause differential damage?

From what I have been told by tire "experts" and mechanics, on four wheel drive vehicles, all four tires should have the same amount of treadwear (tread depth). Uneven tread depth means a given tire's circumference is different ... hence its rotational speed will be different than the others at any speed. That causes the differential gears to absorb the differences in rotational speed which stresses the gears and clutches leading to, ultimately, damage to the differential assembly. COSTLY TO REPAIR

Some tire shops will not sell just one tire for four wheel drive vehicle unless the other tires are within a certain tread depth close enough to the new replacement tire. There are some shops that insist on replacing all four tires - they do not want to be held responsible for damaged differential gears.

 

[bmart]

Using tread depth is reasonable if all tires are identical brand, model, size, etc., but not technically accurate. Circumference is what matters. I've done the viscous coupling. Not cheap. Not fun.