Simple but secure: one stud on each wheel has a lock. Supplied in a set for four wheels. Floor. 18". 17". Driving over rough or damaged road surfaces- as well as debris- curbs and other obstacles can cause serious damage to wheels- tires and suspension parts. This is more likely to occur with low-profile tires- which provide less cushioning between the wheel and the road. Be careful to avoid road hazards and reduce your speed- especially if your vehicle is equipped with low-profile tires.