Du-Bro Treaded Tire 2-1/4" \(57mm\) Part No: 225T. 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. These also have many more applications in school projects and various crafts. Diameter: 2.25" \(57.15 mm\), Axle Diameter: 5/32" \(4 mm\), Weight: 28grams/wheel, Width: 0.775" \(20 mm\).