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-   -   replacing a tire on our awd cars (http://legacygt.com/forums/showthread.php?t=121755)

MRnMRS 09-30-2009 12:10 PM

replacing a tire on our awd cars
 
So this morning I noticed that my right rear passenger tire was really low on air so I drove about 1/4 mile down to the nearest gas station to fill up on air. When I heard a loud hissing sound I knew I had a nail or screw puncture. Sadness. I take the car down to what I was told is a reputable tire shop (Les Schwab) and he told and showed me the 6" nail that poked through the tread and gouged out some bits from the sidewall. More sadness. The tiredude then tells me since I have an AWD car that I would have to replace all 4 tires. Wow are you kidding me? The other 3 tires on the car are fine with less than 12k miles on them.

So my question is, would I be ok with just replacing 2 tires or would all 4 be necessary? Cuz personally I think that's some BS. Or I could be wrong and owe the tirejockey a virtual apology.

Your pals,

MrnMrs

lookslikeanevo 09-30-2009 12:13 PM

tread has to be withint a certian range to not cause damage...a few solutions to this...

buy 4 tires

shave new tire down to same tread as other 3

mightyS 09-30-2009 01:17 PM

Tirerack will shave a new tire and send it to you. You don't need to buy 4 new tires unless they are old or very worn.

MRnMRS 09-30-2009 01:28 PM

Quote:

Originally Posted by mightyS (Post 2641162)
Tirerack will shave a new tire and send it to you. You don't need to buy 4 new tires unless they are old or very worn.

so shaving a tire is pretty safe? I found some threads on here that don't recommend shaving.

the car is an '09 outback (purchased dec '08) with ~12,000miles.

just curious, why isn't replacing just 2 tires an option? i'm new to awd.

krzyss 09-30-2009 02:52 PM

RTFM

You should find a statement that tires' circumference must be within 1/4 inch (or is it 1/2). If new tire has more than this you may fry your AWD system.

Options:
- Manual magic value has probably some safety margin built in and you may be willing to push it; it may be safer to push it on axle with open differential (if you have LSD).
- Shave new tire so its circumference is within SOA spec
- Buy 4 new tires

Krzys

Trax 09-30-2009 02:58 PM

Shaving a tire is safe. I had to do it on a full set back when no one knew who Yokohama was - their tires weren't as round then as they are now! :lol:

wpmarky 09-30-2009 03:28 PM

Your tires need to be within .25" circumference of each other to prevent your diff from frying.

If you only replace 2 tires, the new ones will have less RPM's than your older tires since the circumference is bigger. Your open differential will sense that, and will try send power to the tires it thinks are slipping (rotating faster). Since your new tires will always be bigger, your diff will always be 'working', and may lead to overheating and frying your diff.

MRnMRS 09-30-2009 03:40 PM

Quote:

Originally Posted by wpmarky (Post 2641387)
Your tires need to be within .25" circumference of each other to prevent your diff from frying.

If you only replace 2 tires, the new ones will have less RPM's than your older tires since the circumference is bigger. Your open differential will sense that, and will try send power to the tires it thinks are slipping (rotating faster). Since your new tires will always be bigger, your diff will always be 'working', and may lead to overheating and frying your diff.

thanks for your explanation. thanks to the others too that replied. i also got a hold of my service tech at the and got pretty much the same technical explanation. he recommended that i go to a different shop that they send their cars to and they will measure tread depth on my other 3 tires and make their recommendation based on that. where as les schwab just told me i'd need to replace all 4 with either their house brand tire or some $1000 toyo tourevo's.

krzyss 09-30-2009 07:54 PM

Do not use tread depth measure. Use tape to measure total circumference.
Small error in depth translates to big error in circumference.

Krzys

MRnMRS 10-01-2009 01:33 AM

well.. i dunno what went wrong.. but my wife & i went in to get the Nokian WRG2s

got the Nokian WRG2s

then we said to each other "hey let's check out the new OB 2010s at the dealership down the street.."

got the new OB 2010

what a crazy day.

wpmarky 10-01-2009 04:34 PM

wow congrats, i like the new outbacks too.

NSFW 10-05-2009 12:21 AM

Quote:

Originally Posted by MRnMRS (Post 2642132)
got the new OB 2010

Oh yeah, that's another option when you lose a tire.

With all the options people listed above, I'm surprised nobody mentioned that one. ;)

wpmarky 10-05-2009 09:59 AM

that happened to my friend.

He lost his cup holder liners for his nissan xterra, so one day he goes to the dealership to get new cupholders, and walk out with a new 350z...

!YCAGEL TG! 10-05-2009 07:40 PM

I broke the shifter cable on my 91 Golf, so I bought a 04 WRX

subie_dude05 10-06-2009 11:30 AM

http://www.tirerack.com/tires/tirete....jsp?techid=18


some more info on why we can't get just one new tire. hope it helps


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