i read on super swampers web site that the 36 irok is actually bigger than the 37
http://www.intercotire.com/tires.php?id=6&g=1if you look at OD, the 36 is taller
bias is a softer compound that airs down really well and sticks, but they dont last long on the road at all.
radial is a harder compund that lasts on the road better but not much better than the bias irok...