Tire manufacturers need to store large quantities of tires for their retail outlets. There are so many different tire styles and sizes that it is not possible for a retail store to carry every tire in inventory. Instead, the tires are warehoused at tire distribution centers that are conveniently located near the major metropolitan centers.
However, tires do not stack well. If tires are stacked one upon another on a floor, the stack can not get more than six feet high before falling over. Attempting to stack a pallet load of tires on top of another pallet load of tires results in the whole stack tipping over. Not only is this dangerous, but it also can damage the finish on the tires.
The solution used by most tire manufacturers is to use tire racks. Both passenger tire racks and truck tire racks are designed to safely hold stacks of tires, and the racks allow the further stacking of the tire racks to better utilize the vertical space in the warehouse.