So one of my tires decided to contract cancer... and the bulge has started to make the bead slip. The tread depth difference between my full size spare and the other tires is just over 0.100”. Can I run my spare for a little while without hurting the diffs if I put in the 2wd fuse? Just until I can get a used tire that has similar enough tread depth...

Edited September 17, 20196 yr by Sapper 157

put the spare on the back - front tires should match, and run with the fuse in place - short term only.

fwiw - tread depth has little to do with how the tranny copes - it is circumference that you should be concerned with - the distance around the tire.

Doesn’t the tread depth change the circumference? Therefore I should be worried about tread depth?

technically, yes, the tread depth will affect circumference - but.. it is the overall circumference that will affect the tranny operation - you want all 4 tires to be within 1/4" maximum. a donut spare is NOT going to be the same circumference as a regular tire - even if the tread depth is the same

 

you can have two different tires with the exact same tread depth, yet still be different in measured circumference - this happens frequently with different brands - which is why it is always recommended to have all 4 tires be the same brand, model and treadwear on a Subaru.

Edited September 17, 20196 yr by heartless

Okay got it. Thanks for the clarification. I put the full size spare in the passenger rear and moved the original passenger rear to the front where the bad tire was. Hopefully I can find a used Brigstone Ecopia in town that has about the same wear 

Edited September 17, 20196 yr by Sapper 157