AWD tire size question

LedJetta · Post by **LedJetta** » Mon Dec 20, 2004 2:29 am

i know the whole deal with the diameter of all your tires needing to be very close on an AWD car fopr the system to properly function. i have also heard the subaru AWD system is very sensitive compared to others. my question is exactly how sensitive is it? is it a matter of tenths of an inch or even less?

Post by **Legacy777** » Mon Dec 20, 2004 3:17 am

I think subaru has an official stance on how much difference in circumferences there can be. However I don't remember exactly what it is.

This is an issue to me as well. I picked up a used WRX spare tire so I had a spare to put on that would fit over my brakes. However there's a decent size descrepency between my current wheel/tire setup and the spare.

BAC5.2 · Post by **BAC5.2** » Mon Dec 20, 2004 3:28 am

I think the spec is something outrageously small. Within .25" easily.

I think I even heard people talking that not following proper tire rotation schedules would put a kink in the powertrain warranty. Not that it would be voided, but that it would simply cause hassle.

LedJetta · Post by **LedJetta** » Mon Dec 20, 2004 3:33 am

BAC5.2 wrote:I think the spec is something outrageously small. Within .25" easily.

I think I even heard people talking that not following proper tire rotation schedules would put a kink in the powertrain warranty. Not that it would be voided, but that it would simply cause hassle.

i believe i can work with 1/4" or so. i was just hoping it wasnt something nutty like an 1/8" or less, coo.

anyone know of the exact specs from the horses mouth or where i might find em?

entirelyturbo · Post by **entirelyturbo** » Mon Dec 20, 2004 4:12 am

I actually want to say 1/16th inches, but don't hold me to that

THAWA · Post by **THAWA** » Mon Dec 20, 2004 12:42 pm

http://www.subaru.com/owners/care/carca ... ageID=tire

LedJetta · Post by **LedJetta** » Mon Dec 20, 2004 3:41 pm

THAWA wrote:http://www.subaru.com/owners/care/carca ... ageID=tire

thanks!

entirelyturbo · Post by **entirelyturbo** » Mon Dec 20, 2004 5:37 pm

See? I said don't hold me to that

93Leg-c · Post by **93Leg-c** » Wed Dec 22, 2004 8:27 am

Hey THAWA, thanks for that reference, too!

But, I've got a question and anyone correct me if I'm not viewing this properly. If all four tires have the same circumference and they're all properly inflated, won't the front tires have more deflection or "squash" on them with the extra weight of the car versus the rear tires so that, in effect, the effective circumference of the front tires is more than 1/4" less than the circumference of the rear tires? And, if so, does that mean that Subaru has taken that into account when designing the drivetrain?

THAWA · Post by **THAWA** » Fri Dec 24, 2004 6:15 pm

If you look at the recommended tire pressures you'll see it calls for more in the front than the rear when the load is light in the car. Fully loaded it calls for equal pressures.

93Leg-c · Post by **93Leg-c** » Sat Dec 25, 2004 12:29 am

I'm running 36 psi in the front and 34 in the back. The weight I carry in the car varies considerable and fairly frequently from just myself in the car to fully loaded with equipment to carrying passengers. So, I know the load on the rear tires will vary a lot. Hmmm, I guess no sense worrying about it ...

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AWD tire size question

AWD tire size question