A turning radius gauge is an instrument, consisting of a turntable and an attached gauge, which measures how many degrees the front wheel of a vehicle has turned left or right. Turning radius gauges are often used, during wheel alignment, when measuring caster, camber, and toe-out on turns.

Turning radius gauge turntables are placed under the front wheels. The upper plate in the gauge rotates on the lower plate allowing the front wheels to be turned during an alignment procedure. A degree scale and a pointer on the gauge show the number of degrees the front wheels have turned. On a four-wheel steering vehicle, turning radius gauges are also placed under the rear wheels.