You're ready for your big bike ride. You've loaded your Jeep bicycle rack with your and your riding partner's bikes and this is going to be a challenging ride. To be prepared, you want to bring backup bicycle tires, but your cargo area is filled to the brim. Are you going to make your riding partner sit the entire drive with a lap full of two backup bicycle tires? There's no need to put yourself in such a quandry - 4WD carries roof-mounted bicycle rack tire holders. The sturdy vice attaches to one of your roof racks while the secure clamps hold the backup bicycle tire in place.