You can install a Toyo they have the size to ask by the manufacturer to be 225/50 / R15
Ok I have the general tires and they are installed. Front tires are fine I am running 20 psi in each. I do not like the rear. a little background first, I ride a 2011 electronic 5 speed. I am about 270lbs my wife is average and we have a trailer.
The general is about 1.5 inches taller than the stock tire, gives you a hair more speed per gear for the same RPM. For my personal riding style this is the wrong direction. I do not need more top end speed, I would prefer a little more low end. country roads at 55 mph and I am at about 4500 rpm my bike hates 4000 - 4500 rpm it loves 5000 rpm So I just ordered another new rear tire Hankook 205/50R15 this tire measures 23.1 inch tall. almost 1 inch shorter than stock, this should give a very slight increase in rpm at any given speed. So I will be puttin a brand new General altimax tire up for sale. it has about 10 miles on it. if you are looking to lower your RPM at any given speed by about 50 to 100 rpm this will do it