Can-Am Spyder RT (three-wheel) darkside tire sizes
Stock rear on the Can-Am Spyder RT (three-wheel) (2010 and later) is 225/50R15. Riders report running 225/50R15, 205/55R15, 215/60R15 as a car tire on the rear.
Some Can-Am dealers will only mount the stock tire. Riders report independent tire shops are often more willing.
What riders report
About 30,000 miles per tire against roughly 10,000 on the stock rear, according to one rider on his third.
Several riders like the grip. About the same diameter as stock, slightly narrower. Few high-mileage reports yet.
Reported by one rider.
Car sizes close to stock, on paper
These car tire sizes come within 3 percent of the stock 225/50R15 rear in overall height, by the math alone. They are not rider-tested. Width, rim fit and clearance on your bike still decide what actually works.
Stock sizes come from published fitment listings and owner forums. Check the size on your current tire or the label on your bike, then read the big questions and the mounting guide.