the 120 is plenty wide enough on the KLX. the standard rear tire on a KLR 650 is a 130, and I have run 120s when thats what was available. case in point.... the MT90AT. and BTW, that is a great 90/10 tire (or 80/20?)... my favorite as a "road" tire because in addition to being great on pavement, it has very good manners on dirt & gravel roads and dry trails. its an expensive tire, but worth it if you ride that style. if you're talkin' about doing mud work, then get something else. another tire along that line with a little more dirt cred in the GP1 by IRC. thats where Kenda stole the 270 from. my KLX currently has MT21s because its my more off road bike. the 606 is a good knobbie (didn't like it on the front though). TKCs are really good, but the rear evaporates pretty quick.