What tool is primarily used for measuring tire tread depth?

The tool primarily used for measuring tire tread depth is the tread depth gauge. This specialized instrument is designed to accurately measure how much tread is left on a tire, which is crucial for determining the tire's safety and performance. Sufficient tread depth is essential for effective traction, especially in wet or slippery conditions, as it helps channel water away and reduces the risk of hydroplaning.

Using a tread depth gauge allows technicians to easily and precisely assess whether tires are still within safe limits for use or if they need to be replaced. This tool mainly features a probe that can be inserted into the grooves of the tire tread, providing a quick reading of the tread depth.

Other tools listed, like a pressure gauge, are intended for measuring air pressure within tires, which is important for maintenance but does not provide information about tread wear. A caliper is used for measuring dimensions of solid objects, not specifically for tread depth. A tachometer measures engine RPM, which is unrelated to tire tread analysis. Thus, the tread depth gauge is the only suitable tool for this specific task.