One of the most important components in vehicle dynamics studies is the tire, due to the fact that it is the only component that keeps the vehicle in contact with the ground. In the study of vehicle dynamics, all force transmission between the vehicle and the ground occurs through the contact area of the tire with the road. The maintenance of this contact during the steering allows the driver to have control over the vehicle and this is one of the premises for vehicle safety. The tread grooves help ensure that the friction between the rubber and the soil aggregate is maintained in different lane conditions, be it dry, wet, clean or dirty. Its depth is easy to measure, being regulated in Brazil by CONTRAN in, at least, 1.6 mm. However, even at depths greater than the minimum required by law, vehicle safety can be compromised in wet conditions, as the ability to drain water is greatly compromised at high speeds. There are few quantitative studies on the tire’s state of conservation currently in use in the Brazilian fleet. This work analyzed, through statistical tools, information about the tire tread depth with focus on the vehicle population of the city of Joinville, state of Santa Catarina, Brazil. With the use of a depth gauge, the tread depth has been measured directly on the tires of the sample, formed by ride cars. The results allowed produces an overview of the state of conservation of the fleet of tires, to know the minimum, medium and maximum tread depth. This parameter has strong influence on the vehicle behavior. The care with the state of conservation of tires in passenger vehicles directly reflects the driving safety provided by the vehicle. Choosing tires correctly and keeping them in proper conditions of use is essential for the safety of the car's occupants.