So the bigger the number (70) the taller the tire? How wide would a 265 be then?

 

The width of the tire is indicated by the first number, 265mm, which is about 10.43". (Divide by 25.4 to convert to inches.)
70 indicates the percentage of the first number for determining the sidewall height. 70% of 265mm = 185.5mm. 185.5mm / 25.4 = 7.3"
To get the height of the tire, multiply the sidewall height (7.3") by 2 and then add the diameter of the wheel. So, 7.3" * 2 = 14.6" + a 17" wheel would give you a tire height of 31.6".

Here's an online calculator: http://www.discounttire.com/dtcs/infoTireMath.dos

Hope this helps.
-Jerry

 

it would actually be a 265/75/16 or a 265/70/17, it's the same size tire just rim size is different of course, basically a 32x10.50 tire.