What is the purpose of a tire tread depth gauge?

A tire tread depth gauge is specifically designed to measure the depth of the tread on a tire. This measurement is crucial for determining the tire's ability to grip the road, especially in wet conditions. Adequate tread depth is essential for safe driving, as it impacts traction and can help prevent hydroplaning. Using a tread depth gauge allows technicians and vehicle owners to assess whether tires need to be replaced based on their remaining tread depth, ensuring that vehicles maintain optimal performance and safety.

The other options relate to different aspects of vehicle maintenance. Measuring air pressure is essential for maintaining proper tire inflation, but it does not assess tread wear. Wheel alignment involves adjusting the angles of the wheels to ensure they are perpendicular to the ground and parallel to each other, which is unrelated to tread depth. Checking brake pad thickness pertains to brake system maintenance, focusing on the condition of brake pads rather than tires. Thus, the tire tread depth gauge serves a specific and critical function in tire maintenance.