What does a 315 tire size compare to like 33s 0r 35s?

 

Usually they run around 35". i know 315x75R is some type of side wall and width math equation but i cant remember it.

 

315/75 would be a 35x12.50 i think. But 315 doesn't always mean 35" tall. the second number (75) is the ratio, so that determines how tall the tire is with the first number.

 

315= 315mm tread width
divide by 25.4 to get inches
12.40 inches
315 is always going to be 12.4 inches wide
the diameter of the tire will depend on the following numbers

the 75 refers to the height of the sidewall in percent of the width of the tread.
Each side is as tall as 75% of the tread width

315x.75=236.25mm
236.25/25.4=9.3inches each sidewall
x2 sidewalls=18.6"
add the rim diameter(17")
18.6+17=35.6" tire dia.

So a 315/75-17 is roughly a 35x12.5-17

Make sense?