These are 1-3/4" Super Lite Wheels from Dubro.

Features

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

Includes

Two 1-3/4" 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: 44.4mm (1.750")
Axle Diameter: 3mm (1/8")
Width: 17mm (.671")
Weight: 4.41 grams each wheel