Abstract: A portable device for monitoring the wear of a tire and the geometry of a wheel set of a vehicle has a probe for measuring a depth of each tread groove of a tire, a display, a symbolic representation of a set of wheels, and indicators. The device includes a control system for processing and calculating measurements, reference values and compared values relating to rate of wear and the condition of the geometric state of the tire. Resulting calculations and comparisons are displayed on the display and indicators are activated based on the calculations and comparisons made.