Yep looks like 18" is the standard, so that's what I'll order. Upside is that's the same size they use in autocross, so if I ever wanted to sell them (or switch to autox events), I'll already have the correct equipment.
Dredman... if you want help running the forum or anything like that, let me know. I used to run about a dozen different powersports-related forums. Got out of 'em when I grew bored of ATVs and haven't seen the need to start any new ones lately. :)
'12 Suzuki V-Strom DL650
'10 Kawasaki KLX351S #320
'96 Suzuki DR650
'01 Yamaha FZ1