We just learned a little about Car Tire.
One part of the tire is the Tire Tread.
This is the rubber on the outside of the tire that is in different shapes and patterns.
When there are lines in the tires, those are supposed to help the tire push water out of the way so the car doesn't slide around on the road.
Some tires made for the snow have bigger gaps in the tire treads so the snow can pack in there, and sometimes they even have hard bumps on the outside to help keep the car from slipping.
Tires that are used for racing are called racing slicks, and they have no marks on the tread at all.
After driving for a while, the rubber tread on the outside of the tire will wear out, and the tread will get smooth.
When this happens the tires need to be replaced.
(from: wikipedia - tire tread)
Kid Facts - Blast from the past: Sand Dome
