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Many people here run 19's as their snow tires because they like the look. I personally run 18's which are identical in size to my OEM 18's, but I do that due to cost. I think the only difference between 18/235/60 and 19/235/55 is the 18's will have a 1/2" fatter sidewall and 18" tires are much cheaper.

MP4.2+6.0

It's done all the time by those who just rotate tires off the rims twice a year; I saw it in Europe a fair amount.

Here with a 235 tire the Audi Q5 "regular" rim is just fine; the narrow rim only has an obvious functional purpose as the tire widths drop to below those seen on Q5s. For example my 1996 A6 quattro came with 195s and used a 7" wide wheel.

As another reply suggested, you can also use the Q5 OE 18's, which are yet cheaper in the used market and also fit a 235 tire and are 8" wide in the OE size.

MP4.2+6.0

Here's a link to one of the prior threads that explored the issue. There was a more recent one that seems to be gone, but this has a lot of the details and back and forth discussion as well.

https://www.audiworld.com/forums/sho....php?t=2852924