I don't care one way or another what kind of tire anyone uses, but you should know that the standard bead dimensions are totally different between a car rim and motorcycle rim. What any decent lawyer will make of that is that by mounting a car tire on a motorcycle rim you are not using a product designed to the standard the manufacturer is designing their products to, and therefore they can void the warranty if the tire has any involvement in the warranty claim. It may not matter for an engine issue, or transmission, but you might have a hard time in an accident situation if there is any "traction" issue. Manufacturers generally have the right to nullify a warranty if products (like an aftermarket oil filter) used with their product (the engine) do not materially meet the specifications they have set. It doesn't have to be exact, but there has to be a reasonably conformance to the specifications. In any event, fighting them on a warranty issue can be a real PITA.