These solid wheels were cut from three planks of wood, that had been clamped together with wooden struts. They had copper nails to hold the leather tyres on. But while a solid wheel could carry a load, it couldn't go very quickly. If you wanted organised wheeled warfare, you needed a lighter and faster wheel. It had between 18 and 26 spokes per wheel.
Wheels can be very useful.
After all, in a typical marathon, a wheelchair athlete can beat the fastest runner by about 20-30 minutes. It turns out that wheels do have a few disadvantages. Wheels are good on hard surfaces, but they slow down enormously on thick grass, soft sand, or fluffy carpet. Second, wheels run into problems with vertical obstructions. Try pushing your supermarket trolley over a gutter or curb.