The Crossmark non UST 2.1 120tpi tire shows a durometer of 62. The Crossmark UST 2.1 tire shows a durometer of 62/70 on their website. I know the 70 durometer is the center tread for better wear, but would you be able to tell the difference with grip, etc. between the 62 and 70 durometer along the center tread of the non UST tire and UST tire? With all else being equal. Basically can you tell much of a difference between durometers with speed, grip, etc?