Description Treaded Wheels, 2-1/4″ Key Features     sporty nylon metallic hub    2 per package Overview 225T takes a 5/32 Axle (4mm). Du-Bro’s low bounce captive air wheels have flown on more airplanes over the years than any other wheels on the market! The wall thickness is consistent throughout the wheel giving you a balanced tire. Comes complete with a sporty nylon metallic hub. Works well on grass & paved runways.