Joe, its not by choice I don't believe, but rather the tooling costs. He had access to a 19" setup but to repeat in 18" would involve start up costs of like $50k. I would have gone for 18" too if they had been available, but in retrospect, the 19" really fit the car, do not degrade handling in any way and in fact, because John is able to achieve so much truer a wheel than stock, the 19's are actually a better ride than stock 18's. Of course if John applied the same quality to 18's they would provide even a finer ride.