A push-back rack storage system has a pair of spaced apart rack rails having lower outside rail flanges. A first cart has front and back wheels which roll on the lower outside rail flanges. A second cart has front wheels which roll on outside rail flanges on side rails of the first cart. The back wheels of the second cart roll on the lower rail flanges of the rack rails. A third cart has front wheels which roll on outside rail flanges of side rails of the second cart. The back wheels of the third cart roll on the lower rail flanges of the rack rails. The carts may be provided with a strut deck, a solid deck, or a wire mesh deck, without interfering with rolling operation of the carts.