Check the numbers on the sidewall the higher the number the higher the rating wear, a 400 is a harder and therefore lasts longer, in heat 400 withstands heat better.
A harder tire will be lower in wet traction, not as noticable in dry. If you buy 1000 tires at a time the mfg. will put any name you want on the sidewall.
Most importantly watch your air pressure, I will bet you have one underinflated tire on your vehicle right now.