Ask you hoosier dealer about item 18237, 13.5 x 31.5-15L which is a light weight tire in a similar size as you are running. The also make them in larger sizes but you may need a 14" or 15" wide rim and if you go up in diameter you may need to change the gear ratio.
Bigger tires won't make it faster they may actually slow you down slightly but they will be more consistent.
Check out Hoosiers website.
Your car et's well for the MPH
