my buddy and i are having a debate about how to read a tire and i told him it reads like this .. (example) 265/70/16 is 265mm wide/ 70% of 265mm/ and rim size 16 hes telling me that the serise number is static or is always the same.. like a 205/40/16 has the same size side wall as a 295/40/16. i know hes wrong ive talk to a tire shop and eveyone i know.. and even Goodyears website says thats the formula*. do you guys have any hard evidence or a know of a site that would prove his ass wrong once and for all??? *http://www.goodyeartires.com/kyt/readingATire/

by my calculations, a 265/70R16 has the same sidewall as a 370/50R16 (7.3in) Now a 370/50R16 is an impossible size, but it illustrates quite well, that although both tires have a different aspect ratio, they have the same "sidwall" size.

Maybe a better comparison is: 215/50R16 -- 4.2in sidewall 275/50R16 -- 5.4in sidewall 275/50R18 -- 5.4in sidewall Showing that Radius of rim does not affect sidewall, but the width does.

yes, it means it is roughly 40% as tall as it is wide. 265mm wide 70% as tall as it is wide rolling on a 16" wheel. www.tires.com also has a few good calculators and converters.

not much to prove. the width dictates the sidewall height. if the width remains the same, the sidewalls does also. fyi, x2 on the sidewall calc. for overall height.