These are Lightweight Treaded Wheels by Du-Bro.
FEATURES: Lightweight
Shock Absorbing
Fits inside most Wheels Pants and Retracts
Grey Eight Spoke Hub Design
INCLUDES: Two Wheels
REQUIRES: Nothing
SPECS: Diameter: 89mm (3.50")
Hub Diameter: 4mm (0.15625")
Width: 32.38mm (1.275")