They are made of rubber; most listings explicitly state "Material: Rubber."
Listings describe aggressive BMX knobs, tall knobby treads for mountain/technical trails, smoother rolling treads for around‑town riding, and other optimized patterns intended to improve traction.
Most listings show a package quantity of one tire; listed weights range roughly from 1.6 lb to 2.4 lb per tire.
The listings specify fittings for 20", 26", 27.5" and 700C (28") wheels.
Widths shown include 31.75 mm, 38.1 mm, 57 mm, 3.75 in and 5.2 in.
Listings describe these tires for BMX, mountain, comfort/around‑town, and hybrid/cross bikes.