Are tyres commonly available?

Yes tyres are commonly available and are used for other applications.

A light-weight tyre is most desirable for Chariot Skates. Also, because the skating action tends to wear a tyre out quickly, we have worked with a tyre manufacturer to design a custom light weight tyre using a longer-wearing rubber compound than that used in common tyres. These have have proven to last longer than any other tyres that we have tested. However, these tyres are manufactured using a regular mould, so regular tyres of the correct size could also be fitted to a pair of Chariot Skates if desired.

The rear wheels on a pair of Chariot Skates are just regular commonly available skate wheels.