I‘ve been searching and searching and can‘t find anything that matches a rear tire for my inherited 1982 Honda Custom CM250C. It is listed as 110/90-16 or 110/90S16 - which would be like a 4.25 tire or MP85. Of the few tires I can find on bikebandit and other sites, they all say front tire. I just really want a generic cheap tire to get this learner bike going. I did find the matching sized tubes, just not the tires. The FRONT tire is a 3.25S18 4PR (translates to about a 100/90-18, which I can find).
JC WHITNEY claims 3 different models of tires especially chosen for your motorcycle, and indeed I think they chose a fatter tire for the rear. It's a slender reed, but I think I'd go with it and the Kenda tires. Cheng Shin Barracuda, Street Tread, And Kenda K671 Cruiser tires 130/90-16 Rear K671 Cruiser ST Tire This is speed rated to 130 mph, $58 They have front and rear tires specified. Hope this helps. I took mine to the dealer and said put some new tires on it. Got a fairly nice set of Cheng shins and Tubes though my rims will accept tubeless.
