Here are the diameters of a nice selection of 17-inch knobby tires which are available for sale in North America. All of these tires fit a 3-inch rim.
Shinko 244, size 5.10-17
Diameter: 25.63 inches, or 651 mm
http://www.shinkotireusa.com/tire/244-series
Shinko 700, size 5.10-17
Diameter: 25.63 inches, or 651 mm
http://www.shinkotireusa.com/tire/700-series
Kenda K270, Size 5.10-17
Diameter: 25.9 inches, or 658 mm
https://www.denniskirk.com/642024.sk...utm_medium=cse
Kenda K760, Size 130/90-17
Diameter: 26.3 inches, or 668 mm
http://www.kendatire.com/en/motorcyc...trakmaster-ii/
__________________
Spud
"Never argue with an idiot. He will drag you down to his level, and beat you with experience."
Mark Twain
2015 Zongshen ZS250GY-3 (RX3)
2006 Zongshen ZS200GY-2 (Sierra 200)
2005 Honda XR650L
2004 Honda CRF250X
1998 Kawasaki KDX220
Mods made to my Zongshen ZS200GY-2:
http://www.chinariders.net/showthread.php?t=6894