My main question is about the degree of tolerance, if any, that the Torsen diff will allow in a Quattro setup. I have a 1998 B5 1.8TQM and am unable to pay for a brand new set of tires. I do however have a set of two used tires that are maybe 70%.

Is it possible to run 205/60/15R tires up front and 195/65/15R in back, or vice versa? I know that Audi specifically states that running differing size tires will adversely effect the Quattro system (read: blow up your Torsen diffs), but when I called my local dealership and even Audi of North America, they were only able to tell me what size Audi recommends

I've compared the two tire sizes on Tire size calculator and the difference between the revolutions per mile seems almost negligible (817 versus 807). Difference in circumference is .9 inches.

I'm not trying to put any more than maybe 1000 miles on this setup, as it is a band-aid fix until I have the money for a set of new tires. Any help/suggestions/recommendations would be GREATLY appreciated.

 

I'm curious about other thoughts on this subject. I recently purchased an a4 with quattro and it has 18" rims on the rear, 17" up front.

How much deviation in tire sizes can the car handle?

 

3% in the rolling diameter of the tires.