tire size

hey guys just got the Old Man Emu kit. Now its time for winter and it dose get very cold here. - 20 c - 25 c. I'm thinking 245 70 15, 255 70 15, 265 75 15. Im running 235 75 15 cooper LT. plus I have some Gateway Gombo mudders with a size that only says 12/15 12 wide 15 rim do any of you now how to tell how to size that. bias ply

id say take a tape and measure the height of the tire and if it comes out to like xx.3 or something, round the number up, i might be wrong, but just a suggestion..

Edit: try this link http://www.liquidoffroad.com/groundhawgbias.htm Appears to be a 33"