the tread is part of the tyre that is supposed to touch the ground
so that the car won't slip
No, tires have treads.
because it helps the car when driving
we need rough tyres to increase friction
Yes, all vehicle tires have treads on them. Truck tires will usually have larger and deeper treads than regular sedans.
Look for any bulging or if the car moves rough like there is pulling on the wheel while driving. Also any wear to the treads.
Because constant use wears the rubber away from the treads.
The answer is: have
Pro Comp makes various Xtreme terrain tires for vehicles that need offroad performance. The tire treads on Pro Comp tires are very different from regular car tires and cost a pretty penny, too.
Tires are pro-rated based on the amount of wear they have. This is largely determined by the depth of the treads.
Because the rubber in tires was being used for war supplies including tank treads and jeep tires.
Because the tire is very thin when there are no treads unless they are racing tires and it is very dangerous
Here is a good article that covers a lot of issues with tires:http://www.ehow.com/how_5077858_check-tires-maintain.html