I have a 2019 A6 with 21" wheels and am driving in a climate where the weather can be cold and icy in the winter. There are no all season 255/35R-21 tires on the market but I have found a Pirelli 255/40-R21 tire.

While the gear speedo won't be completely accurate with the 40s, is there a problem with using that tire that I am missing?