I destroyed a back tire on my 2008 Subaru Impreza manual transmission with viscous coupling.
The manual says all four tires must be the same size. The spare tire must only be mounted onto the rear axle when applicable. I don't need to pull a fuse to disable AWB on my manual, but automatic transmissions do.
I talked to a tire mechanic who has been doing this for decades. He says that I do NOT have to replace all four tires with new ones. He said replacing just the single blown rear tire with a new one (same general size, but different brand and likely slightly different circumference) will be totally fine. He says he has never had any problems doing it on other Subarus. In fact, the spare tire that I was running on WAS of a different size and it ran on it just fine for 75 miles and no warning lights.
In this case, is it ok to drive around with one new tire on my Subaru? Or do I still have to replace all four?
The mechanic said that as long as the tires are all of the same size (205/55/16) little differences in tread depth and manufacturer differences won't matter.