If you want high mileage, look for highway duty LT tires like XPS Rib, or HT tread pattern tires from Goodyear and Bridgestone/Firestone. These tend to use harder tread rubber compounds, have wear enhancers blended in, and put more rubber on the ground.
If you have severe winter driving conditions, you might consider true winter tires (MS, MS2 are not) as a second set. All Season tires are a compromise between mileage and weather (and or off-road) capabilities, and all season tires marketed as MS go the farthest toward winter capability by using softer compounds and open blocky tread patterns, without actually getting tobwinter tire capabilities.
Towing is particularly hard on MS tread patterns, the constantly shifting side loads mean a lot ofvtread block squirm.
