Discuss. Wheel Specs: Rim, front 2.15 x 21" Rim, rear 4.25 x 17" Tyres, front 90/90 - 21 54V Tyres, rear 150/70 - 17 69V I'm wondering if anyone has yet fitted a 130 width rear to the 800 yet. There are substantially more (and cheaper) knobby options in the 130 vs the 150. With a 4.25" rim, that may be stretching it a bit (literally), though? Also, what are the implications of changing tire sizes WRT the ABS system?