this post was submitted on 26 Aug 2026
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me_irl
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For an all time AWD system like what Subaru offers, you will need to do this if the replacement tire is worn, or shave it to match.
Subarus are actually one of the worst-case vehicles for this. I really don't understand the love for those things.
My partner has one and with the 'need to replace every tire if you replace one' thing, ads showing up in the infotainment center, the battery dying if the key fob is stored too close to the car (real stuff, it's legit written in the manual not to store the key near the car because of this, ask me how we know), she's so fed up with it.
Edit: To clarify the 'one of the worst case', other AWD/4WD vehicles have higher tolerances for size mismatch than Subarus. Like, I think literally every other major manufacturer is better about this.
Yup, having only ever driven Subarus, this is what I have always been told. The ever-so-slightly different diameter of a worn VS new tire can cost you way more money than a three additional tires in the long run.
I dunno... With tire prices the way they are these days, servicing the center diff might actually be cheaper than replacing 3 additional tires. Especially if you're doing it yourself.
You just need to replace 2, not all 4.
Depends on the AWD system. If there's a center diff or a clutch in the center, the speed differences where the front axle and the rear axle meet can cause excessive wear and heat. Subarus are the most common vehicle for this, but some high end German stuff I know can have issues as well. But generally economy cars and midrange cars disconnect the extra axle or have a loose coupling to it, so only two tires replaced are fine.
Every certified Subaru mechanic and mechanics working directly for Subaru have always said I only needed two when one tire needed complete replacement for my Forester.
As long as they are within 1/4" diameter variance this is true, otherwise you FUBAR the viscous coupling over time. Which is why most mechanics default to 'just replace all of them'.