Why Check Tire Air Pressure?

The Tire Rack Street Survival teen driving schools authorized by the BMW CCA Foundation are intended to provide a controlled environment for young drivers to learn car control by experiencing their vehicles' handling and stopping capabilities. Street Survival driving courses are typically set up on large parking lots and use traffic cones to define the intended driving path and control the flow of traffic.

However before participating in any of the Street Survival hands-on driving schools conducted on the test track at the Tire Rack's headquarters in South Bend, Indiana, the first lesson the young drivers learn is how to maintain correct tire pressures. Maintaining a vehicle's tire pressures allows the tires to effectively support the weight of the vehicle, occupants and cargo while contributing to its ride, handling and traction capabilities.

Immediately after signing in upon their arrival, participants are directed to have their vehicle's tire inflation pressures checked with the help of their Street Survival coach. This allows the coach to show participants the vehicle manufacturer's recommended tire pressure listed on their vehicle's tire placard or in its owner's manual, as well as provides the Street Survival participants the opportunity to use a tire pressure gauge and air hose to check and reset pressures.

Note: Because the Street Survival teen driving course is intended to allow the participants to learn the capabilities of their vehicle as it would be driven on the street, higher than standard tire pressures are not recommended since they will artificially and temporarily enhance the responsiveness of the vehicle.

While the Tire Rack team agrees with the National Highway Transportation Safety Administration that tires are all too frequently driven on while underinflated, we wanted to study a real-world example of our own. In order to document the tire pressures used on a random sample of consumer vehicles, our Street Survival coaches have been recording the tire pressures of vehicles as they arrive at the Tire Rack.

The following analysis is based on that data. However because these tire pressure checks are typically conducted between 8:00 to 9:30 AM shortly after participants arrive (rather than first thing in the morning before the tires have been driven), it cannot take into account the subtle increase in tire pressure that results from rising ambient air temperatures or the increase in tire temperatures generated by driving. Combined, these two influences could increase tire pressures by about 3-5 psi above their cold readings depending on conditions.

Even when assuming that changes in ambient temperature and driving distances had a minimal influence on the tire inflation pressures when they were measured, only 59 of the 280 tires checked were correctly inflated!

The lowest tire inflation pressure measured was just 9.5 psi (20.5 psi low due to the tire having been punctured by a previously unseen nail)! The highest pressure was 58.5 psi (23.5 psi high blamed on a faulty air pump pressure gauge at a gas station).

While maintaining correct tire pressures is a common problem, these results emphasize how little importance drivers place on maintaining them.

The Tire Rack recommends that all drivers check and adjust cold tire inflation pressures at lease once a month or before taking any extended highway trips.