Depends on the brand but about 130mm for a stock width rim.
Each tire manufacture will tell you the width of the rim required for the tire width.
Also the tire when inflated has to fit in the swing arm with out rubbing.
You should have checked that out before lacing up a rim to the hub.
I spent two weeks of internet research and phone calls on that same project.
My choice was Avon Road Rider 26's. 130mm on the rear. Reversible on the front.
Track racers also liked this tire because the rubber was not too hard but not too soft.
Front tire.
Rear tire.
On a Roadstar Adventure.
Locked
