🛞 Foam Tire
A tire moulded from solid foam rather than rubber, used mainly for on-road and carpet racing.
Light and very grippy on smooth surfaces, but they wear down as you run them and are not durable off-road.
What it actually does
Foam tyres are solid moulded foam rather than rubber with an insert. They are the standard on high-grip on-road surfaces — carpet and asphalt oval and pan-car racing — because they offer enormous, extremely consistent grip and almost no sidewall flex.
In practice
Foams are chosen by durometer (hardness) and are usually trued on a lathe to a precise diameter before use. Because they wear down as they run, their diameter changes, which changes rollout — racers plan for that across a race day.
Worth knowing
Foams are surface-specific. On dirt or anything abrasive they wear away quickly and grip poorly, so they are the wrong choice everywhere except the surfaces they were designed for.