Cascade-LGT Posted October 1, 2004 Share Posted October 1, 2004 I just bought a set of used Nokian Hakka 2s off eBay. 2 are almost new, 2 are very worn (I was assured by seller they were of equal tread depth, but thats another story...). If I'm unable to recover my money, I'm contemplating buying 2 new tires to go with the 2 good ones. There will be 2/32s to 3/32s difference in tread depth. Does anyone know the tolerance of the Subaru AWD system to tread depth variance? Thanks. Link to comment Share on other sites More sharing options...
TLS Posted October 1, 2004 Share Posted October 1, 2004 You could always compensate with tire pressure on the worn ones or vice versa. I don't really think its all that important. Link to comment Share on other sites More sharing options...
Cascade-LGT Posted October 1, 2004 Author Share Posted October 1, 2004 Thanks, but I've had tire installers refuse to install tires which were of significantly different tread depths on the basis it would damage an AWD system. I believe it does make a difference. I disagree with you but thanks for the response and idea... Link to comment Share on other sites More sharing options...
TLS Posted October 1, 2004 Share Posted October 1, 2004 The viscous coupling center differential will absorb the VERY slight (2-3/32's) difference. Anyone know what difference that would be in revs per mile? Would I knowingly buy just 2 tires and try to match them to already worn ones? .......Probably not. But it would not harm anything. I checked tire pressure the other night on the LGT. 3 were @ 31 psi one was @ 34. I bumped them all up to 34. How many people don't check tire pressure? I watched the wheel raise visibly with those 3 psi. You cant visibly see 2/32'nds. Link to comment Share on other sites More sharing options...
TLS Posted October 1, 2004 Share Posted October 1, 2004 2/32'nds of an inch difference is equal to MAYBE 10 more/less revolutions per MILE. You'll have more diameter variance in two BRAND NEW TIRES than this. Link to comment Share on other sites More sharing options...
Cascade-LGT Posted October 1, 2004 Author Share Posted October 1, 2004 Good point on the materiality of 2/32s and the fact most people do not regularly check tire pressure. So there's probably many, many AWD vehicles out there that have significant differences in rolling diameter, apparently without doing damage to their AWD systems. Your logic is sound. I'm equally sure that Subaru has a "recommendation" specific to tire wear and when the difference does become material. I'm just looking for that number. My situation improved as the eBay seller is willing to take the tires back or refund me the difference. So I can probably get the two good tires real cheap if I'm willing to match them up with 2 new tires and your point makes that look more appealing. Thanks. Link to comment Share on other sites More sharing options...
Ken S Posted October 1, 2004 Share Posted October 1, 2004 Rather than tread depth, the circumference of your tires is a better indicator of it's affect on the AWD system. We actually got a firm answer from Subaru of America over at Edmunds, but I don't recall what the exact measurement was. I *think, but not 100% certain* that it was 1/4" difference in circumference measured over the same section of the tire. I'll see if I can dig that spec up. Ken Link to comment Share on other sites More sharing options...
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