Firestone Coil-Rite Air Helper Springs Firestone air helper springs are designed to fit inside existing coil spring suspensions, creating a variable rate spring. These air helper springs are made of durable, elastic polyurethane providing years of comfort and stability to your vehicle. Coil-Rite air helper springs provide extra support for coil springs in cars, minivans, vans, light trucks, RVs and SUVs. The complete adjustability of these air helper springs will level your vehicle, provide a smoother ride, more effective braking and handling, even under heavy loading and adverse road conditions. Firestone's Coil-Rite air helper springs enable adjustment for varying loads and road conditions by inflating or deflating the air helper springs. Spring performance can be altered as easily as inflating a tire. The air springs will support 500-1000 lbs per set.(Note: Do not exceed the vehicle. Firestone") warrants that its Ride Rite Air Spring Assembly will perform according to the manufacturer's specifications for as long as the vehicle on which the system was originally installed is owned by the original retail purchaser..