This is the Du-Bro 200R Low Bounce 2in Wheels 51mm (2)

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. 2/pkg.

These also have many more applications in school projects and various crafts.

Cat. # - Diameter	Axle Dia.	Weight	Width
175T or R - 1.75" (44.45 mm)	1/8" (3 mm)	13 grams/wheel	0.675" (17 mm)
200T or R - 2.00" (50.8 mm)	1/8" (3 mm)	17 grams/wheel	0.750" (19 mm)
225T or R - 2.25" (57.15 mm)	5/32" (4 mm)	28grams/wheel	0.775" (20 mm)
250T or R - 2.50" (63.5 mm)	5/32" (4 mm)	36grams/wheel	0.875" (22 mm)
275T or R - 2.75" (69.85 mm)	5/32" (4 mm)	43grams/wheel	0.900" (23 mm)
300T or R - 3.00" (76.2 mm)	5/32" (4 mm)	58grams/wheel	1.030" (26 mm)
325 T or R - 3.25" (82.55 mm)	5/32" (4 mm)	79grams/wheel	1.150" (29mm)
350 T or R - 3.50" (88.9 mm)	5/32" (4 mm)	99grams/wheel	1.250" (32mm)