AWD car needs a new tire; Replace one or all 4

because that's what FHI requires.

That's what you'd like to believe. But it is does not make it right. If it makes you feel better I see subarus and quattro outfitted audis run on single axle brake force testing contraptions right and left. (during annual technical "inspections" for example)

I never saw a gadget for testing brakes in a US of A auto shop, not the one that spins two tires at the time (ruining awd hardware on subarus).

I specifically do not buy a used subaru because of the cheapskates like you: one never knows what thew center diff was subjected to.

I immediately thought of a guy here who run mismatched tires on front and back axles of a quattro audi (torsen based one, not haldex crap based one obviously).

the drivetrain was making all sorts of noise to a point that snake oil salesmen offered to ditch the driveshaft essentially converting the car to fwd.

all the noise was gone once the guy had installed 4 matching tires audi requires.

the drivetrain on subaru would've been probably ruined by the same treatment but torsen seem to take this kind of abuse better, or so i would like to believe

With AWD you replace all 4 at the same time.

The "concept" is reality on an AWD vehicle.

Well then. It is what it is. Is it possible to buy a new tire and have the tire shop shave the tread down to match the other three?

Wasteful as it is, it seems like a proper solution. Otherwise, I'll replace all four.

Thanks.

-J

Have you considered fitting an inner tube to the tyre with the leak?

A good shop should be able to shave the tread. But finding a good shop is a crap shoot some times. If you can find one that does race tires or handles a lot of ricers you would probably find a shaver that knew the work.

Yes. But you'll probably have to find a race shop to do the shaving. And they will refuse to do it once the tire has actually been operated on the street (because the rubber of the tire tread will pick up debris that will destroy the knife on their machine,) so you would need to take the tire over to them in the trunk of another vehicle (possibly with one of the old tires so they can measure the tread depth on it with the same gauge that they're going to use when they shave your new tire.)

Where are you? If you are in NoVA I can ask around, I have some contacts that might know where to have this done.

good luck

nate

DING DING DING No more calls, we have a winner with the obvious answer.

This practice was common once, years ago, but the lemmings have since been easily convinced that they need to replace the tire. Yes you'll get more heat buildup but somehow I suspect you're not racing that greyhound and that will never be the slightest issue for you.

"Here are recommendations from some of the manufactures that Tire Rack currently serves for matching the tires used on their four-wheel drive and all-wheel drive vehicles.

Subaru- Within 1/4-inch of tire circumference or about 2/32-inch of each other in remaining tread depth."

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- gpsman

are you driving on road? if so, you're absolutely correct about the "concept and theory", so it's a small step to proceed on how you make your decision:

1. determine cost of a rebuilt transmission.

1. determine cost of a set of tires.

if 1 > 2, proceed with new tires.

if 2 > 1, proceed with new transmission.

simple.

now, if you're driving off road, then it's different - circumference differentials get lost in surface slippage, so a new tire is not a problem.

Could you even get an inner tube in the US or A?

I had a brake shop suggesting to machine the rotors when all i needed was a brake pads. A quick: "would you like me to sign the release of liability?" brought them to their senses. The front office clerk commented he never machines his rotors either.

that was probably an unrelated aftermath of the incident.

with mismatched tires i'd expect the damage localized to the center diff and possibly rear diff (which impreza ts normally does not have anyway, so that's off the plate)

like you implied it's hard to imagine how torque bound center diff could propagate the strain through the

5sp gearbox all the way to the engine

call around to a few used tire shops or junk yards and see if they might have a IDENTICAL used tire laying around. Then compare heights Its a long shot , but you might get lucky.

My question to whomever has a car like this: Do the front and rears

100% symmetrically wear? If they don't, there will be some automatic changing difference front to rear from fresh off the rack until the tread wear indicators hits.

One thing i have noticed is just because a tire says a certain size, that does not mean all brands are 100% identical height for the the same size on the sidewall.

bob

that's another reason to change the tires as a set of 4wd's. you have to do that at least for the same axle on 2wd.

none of my local shops stock them. i suspect for precisely the reason hoof headed cites but then dismisses.

just change the pads yourself. you can buy new disks with the money you save. if you ever need to.

Yes! Goodyear Tire and Auto Centers even stock them!

I always check with a dial indicator; if it's fine (which it almost always is), I don't machine them. I don't get why people want to remachine them every time.

--scott

it's a service they can charge for, and it's "cya".

Fixed it for you.

HUH?? ALL of the AWDs have rear diffs. You have a front differential inside the trans, That feeds power to the front wheels. The same shaft that turns the front ring gear also turns the center differential/vicuous coupling, hydraulic/electronic clutch (model dependent on what you have)that is located at the output shaft housing. From that power goes back through the drive shaft to the rear differential. Without a rear diff. they would eat tires like crazy.