These are Dubro 3" Super Slim Lite wheels. Super Slim Lite wheels were designed for most ready to fly vehicles that need a larger diameter tread wheels to taxi and take-off from grass fields. The wheels are slim to fit onto short and small diameter axles.
Axle hole: 0.118" (3.0mm) diameter
Width: 0.645" (16.4 mm)
Weight: 8.8 grams/ea for the 275SSL ; 10.2 grams/ea for the 300SSL