The UTQG treadwear number is one of the trickiest things on a tire. It is supposed to measure treadwear, but every brand sets its own numbers, and they are not easily compared. Generally, the lower the treadwear, the more grip the tire has, but even then it is not a reliable measurement. As technology advances, tires may have both better grip and longer wear than a previous design or a tire from another brand.
Guessing grip from a treadwear number is like guessing horsepower from fuel economy ratings. More of one usually means less of the other, but sometimes technology allows both to improve simultaneously.