I recently bought a set of Bridgestone Potenza RE960AS Pole Position tires in stock 205/55R15 (W speed rated) for my 2004 Subaru Impreza WRX. As I was scanning through the Tire Rack (that's not where I got my tires) listings for this tire, I saw the different speed ratings for different sizes of the same model, or even sometimes the same size in the same model. My size is just where RE960AS goes from H speed rated to W.
So is there anything different about the construction or materials that would make mine W rated? Maybe just certain dimensions or maybe there isn't that much of a difference? I'm really curious about tires where the same model/size is sold with two speed ratings. The Michelin Pilot Exalto A/S was about $40 more for a V rated tire in my size compared to their H rated version.
I like reading the Tire Rack reviews, but sort of take their numerical rating system with a grain of salt. People are assessing these tires on different cars with different sizes and different expectations. I wonder when some Summer tire that I assume would have some incredible grip gets a higher dry traction survey rating than a better than average all-season performance tire.