When talkin tire size what is the difference between say tires with numbers like 285/70/18 and then numbers like 35/12.5/18?

 

285/70/18 is measured in milimeters and is usually used for all terrain tires. The other is measured in inches usually used in mud terrains. At least I think so.

 

There are two sizing systems. Metric and floation. In floatation sizes, like 33x12.50-18, the first number is the height of the tire in inches, the second numper is the width of the tire in inches and the last number is the wheel size. So a 33x12.50-18 would work out to be a 305/60-18 tire.
In the metric system, like 285/70-17, the first number is the width of the tire in millimeter, the second is the percentage of the tires height in relation to it's width and the last number is the wheel size. So a 285/70-17 is essentially a 33x11.50-17.

 

lol, How many times have you had to type out that exact paragraph Wandell? I quit even trying to explain metric/flotation. (I learned by searching Google and READING)

 

Several times, but I understand the search feature here isn't exactly the best.