These are 2-1/2" Super Lite Wheels from Dubro.

Features

Black impact-absorbing foam construction pre-mounted.
Gray plastic eight spoke rims.
Five Rib tread design.

Includes

Two 2-1/2" Super Lite Pre-mounted Wheels

Requires

Wheel collars to hold them on the axle.
May require reaming out the hole to mount on larger axle.

Specifications

Diameter: 63.5mm (2-1/2") O.D.
Axle diameter: 4.4mm (.175")
Overall width: 20mm (.788")
Weight: 9.65 grams each