Can you elaborate on why winter Tires have no Uniform Tire Quality Grade rating?
Winter tires are not assigned tread wear ratings.
Winter tires are designed for cold weather use only. Usually when average daily temperatures are at or below 45* F / 7* C. While the tire operates just fine in warmer conditions, it will wear out very quickly.
Therefore, the life of the tread is impacted by the amount of driving performed in warmer conditions since the rubber compounds that give this tire winter grip are not designed to withstand non-winter conditions over the long-term. In short, winter tires used in the summer wear out very rapidly.