Set of Two. Replace flat kayak cart tires with new. 3 inches wide x 13 inches diameter. Malone Airless tires should fit a range of kayak carts. Comes with adapters to fit 7/8 inch to ¾ inch axles. Axle must extend about 2 7/8 inches from cart frame to the hole for the Axle Quick Clip Pin (not included). The axle hole in the hub is about 2.5 inches deep. Formerly part number MPG-506. Sold as a pair.