See also:

Tire tread
WARNING Although the applicable federal motor vehicle safety laws consider a tire to be worn when the tread wear indicators (TWI) become visible at approximately 1/16 in (1.6 mm), we recomm ...

Tread wear
The tread wear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified U.S. government course. For example, a tire graded 150 would ...

Installing the ball coupling
WARNING If the vehicle/trailer combination is not secured, the trailer may come loose. As a result, you could cause an accident. Therefore, make sure that the ball coupling is secured with th ...