A few days ago, while out Christmas shopping, I got a flat on one of my new-to-me 16" Dunlop M3 winter tires. (Bought them used from another AW'er. Tires have about 12k miles on them, and still look great, but the flat tire got ruined beyond repair). They were only on the car for two days when it happened too!

So right now I have one of my 17" A/S tires on the car. It's in the front where I got the flat. I ordered two replacement 16" M3s from Tire Rack's final stockpile of these tires. But they are coming from the Nevada warehouse and won't be here for another week or so.

I'm thinking of putting two of my A/S tires on the back of the car, and using both snows up front. We'll be driving a total of about 150 miles over the next few days. Take my car with the mismatched tires? Or take my wife's car? It's a '95 Subaru Impreza with four good BFG Traction TA A/S tires.

-- P.

Unless it was an emergency, I wouldn't drive my car with partial snow tire coverage on it, let alone with different size tires... The tolerances on the AWD diff are very tight for wheel size; even mixing new and well-used snows of the same size and pattern could put a lot of wear on the differential over distance.

Personally, I'd run all the same tires on the quattro or take the Subaru. I don't know what the traction control setup would be on a '95, but if it doesn't have it, then I'd go with the quattro.

Good luck, and save travels!

I know that running diff size tires is bad for the drivetrain over the long haul. But my holiday visiting will be less than 150 miles. So I was wondering what the break point is. Obviously we have spare tires in the car to get us home. And not that long ago, Audi used a donut spare (I had one in my B5). The rolling diameter between a 235/45-17 and a 215/55-16 is pretty darn close.
Hopefully my new snows will be in next week.

-- P.

Using dramatically different tires on each axle is not a good idea. It'll get you to the grocery store, but obviously in a less than desirable scenario, the results could get ugly. In snow and ice, I'd want the all seasons up front and snows in the back. You don't want that back end getting away from you. In dry weather, I'd want the all snows up front and all seasons in the back for the same reason. Obviously you can't have it both ways. You'll be fine with all seasons all around.

Just 2 days ago I made a subaru commercial 4 miles from my house on the way to work. Didn't realize a box the size of a refrigerator had blown into my lane (don't ask, but I was half asleep and preoccupied with an SUV that looked like they were about to do something stupid). Not knowing if there was anything of concern in that box, I didn't want to hit it head on.... When all was said and done, I was back in my lane on the other side of the box, SUV driver nearly shat his pants because I was headed right for him at one point, tires howled more than enough for my comfort, and the adrenaline replaced my need for coffee that morning. 2 different sets of tires in that scenario would have ended differently. No doubt in my mind.

OTOH, you could drive the Subaru...but you have that beautiful Audi sitting in the driveway....!

Have a good holiday Peter!

Not a major difference. But as long as the rolling diameters of the tires/wheels are the same, its not going to frag your diff!

Do what Raj said if you can.

Tire shops constantly rip people off with this one....I rolled in to get a tire patched on a 19" rim with spare @ 18 on the car and the other 3 at 19"....take the tire in and the inside was a little warn and they said they could not patch it...<cough> BS <cough> BS...then said I should replace all 4 tires since it is bad on AWD cars. I just looked at them and no thanks and walked out and had my buddy patch the tire for me. What a con job they pull. I felt like saying I have been driving my car with 18" for 2 days and it seems to be working just fine....but then that would be a waste of effort to say that. Everyones trying to sell something. I know big rolling diameter diff is not ideal but between same size tire and just worn and new is total BS.

The rolling diameter between my 18 spare and 19s with low profile are close.

I'd get all seasons, or a second set of wheels/tires if ou want to take the B7