>>I'd like to begin a 5-tire rotation on my syncro so that I can get some
>>mileage out of my spare. I realize that syncros require identical size tires
>>on all four wheels to prevent viscous coupler damage. Is there any risk in
>>putting my brand new spare on when the other tires have about 10K miles on
>>them?
>
>I don't think so and I sure hope not.  I've just done the same thing on my
>van.
>

With a 27" tire diameter, a difference of 1/8" in tread depth corresponds to
a difference of less than 1% in circumference:

(.250) / 27 = 0.93%

I can't find any specs in Bentley regarding tolerances for tire
circumference on syncro vehicles, but a 1% difference sure doesn't sound
like it would be enough to matter.

-Mark McCulley