Worn car tyre. Close-up of a car tyre with a bald (worn) tread pattern. The tyre is made of rubber. The tread pattern, consisting of grooves in the rubber, helps direct water away from under the tyre. These grooves are lost over time due to wear and tear on the tyre, meaning it needs to be replaced with a new tyre. A worn tyre is dangerous because it is less able to grip the road surface and could cause an accident.