Review on 🛠️ Deli Tire Lawn & Garden Inner Tube with TR87 Bent Valve Stem for Wheelbarrows, Tractors, Mowers, Carts (4.10/3.50-4) by John Miranda

It's butyl rubber. If you bought a fully inflated spare tire from a discount store for less than that tube alone, I'm pretty sure there's a cheap nylon tube in the wheel. In principle, it is no better than a child's pool toy. It probably won't last four seasons and there's no point in trying to patch it or using Green Slime on it. On the other hand, this product is a real inner tube, made from the same material as conventional bicycles and utility vehicles.