IT KICKS ASS! I initially put Kenda Sport Challengers on my XR650R. For those who haven't heard of them, they are a standard size... 21" in front, 18" in rear road tire. DOT approved. Street-style tread pattern. Unfortunately, they don't hook up in the twisties like I had hoped. I really wanted to avoid spending 1000 bucks on a wheelset. Anyway, the Kendas sucked and made me feel very nervous when slamming into the turns, so I finally built up the balls and called Paul Brent at Moto-Master. I've had my 17s (Excell rims, Talon hubs & spokes) installed for 2 days now, running Metzler Sportec M1s (120/70 up front and a 160/60 in the rear). The difference is literally unimaginable. My bike handles like a beast, slicing and dicing through the turns... holding its own against all the GSX-Rs, CBRs and Ducatis. All day today, I ripped through canyons and along the coast, trying to find my new traction limit. I baaarely broke traction ONCE all day. The XR cornered hard and confidently. No skiffing rear end. No sketchy fishtailing. This thing puts my F4i to shame aside from the straight-aways. It's really impressive. Thanks for the fair deal and high quality gear, Paul! For all who don't know, Paul Brent has special deals for Thumpertalk people. I highly suggest giving him a call and spending the money to convert your bike if you've been putting it off. The difference is night and day. Oh yeah... my 39-tooth rear sprocket is good up to 90mph.