What does the term 'pneumatic tire' mean?

Answer 1

Pneumatic means "containing air", so a "pneumatic tire" means just that: a tire which is full of air.

Such tires are made of a flexible rubber compound, about the same shape as a big ring doughnut, that has to be made the right size to fit a particular size of wheel rim. The tire must have a one-way valve to allow it to be pumped full of enough air under pressure to make it roll smoothly whilst absorbing bumps from uneven road surfaces, pot-holes, etc. - yet no so hard that it bursts!

Well before pneumatic tires were invented, tires made of wood or iron were fitted to stone, wood or metal wheels to make the wheels last longer. If you don't have a separate tire, the whole wheel has to be replaced when its outside edges get chipped and worn away. So it is probable that tires were invented very soon after wheels because the people who invented wheels found out it was a good idea to have tires on them which could be replaced when they wore out.