Lite Flites are one of the most popular robot wheels due to their very light weight and surprisingly good traction.

The tires are made from thick, durable foam mounted on sturdy hubs. The injection molded snap-together hubs securely lock the rubber to prevent free-spinning tires.

Since these are "soft" wheels, they are excellent at preventing shock from destroying delicate gearmotors.
Mounting these on a motor? Lite Hubs make quick work of this.

Bores can be drilled up to 3/16" for larger shafts.

Width: 0.75in (19.05mm)
Bore: 5/32in (3.97mm)

Diameter: 1.75in (44.45mm) 2.00in (50.80mm) 2.25in (57.15mm) 2.50in (63.50mm) 2.75in (69.85mm) 3.00in (76.20mm)

Weight (each wheel): 8.51 grams (.30 oz) 10.49 grams (.37 oz) 12.76 grams (.45 oz) 15.31 grams (.54 oz) 18.71 grams (.66 oz) 22.11 grams (.78 oz)