Many, if not most people in first world countries do not buy motorcycles as their daily drivers or primary vehicles for commutation, sonny. While car tires on motorcycles might provide some economic advantage for some, they also provide a false sense of security for those that limit most of their motorcycling mileage to straight and level roadways or on any other common roadways and conditions, for that matter.
Whether a rider wants to admit to or acknowledge the safety compromises that are attendant with mixing MC tires and rims with those designed for cars or vice versa, well, its still a free country, so have at it. The risks are valid and incontrovertible, IMO. This is pretty much an analog for what sort of helmet is the smartest choice for motorcyclists. It's still a matter of choice, regardless of any bothersome facts.
