WannaC5Z

Hey guys I know how to figure the aspect ratio of regular tires, but what about a size like 305X645X18? What is the "645" representative of? Is it the height of the tire? I am trying to find some used rear racing slicks and found a decent deal on these. A 305x35x18 would be the standard size I would want. The 35 represents the sidewall is 35% of the 305mm track width of the tire. But what about the 645?

blkbrd69

645mm height = 25.3937"

WannaC5Z

Cool...that is what I figured.

GT Racing Tires

Metric number divided by 25.4 will give you actual size in inches.