Tire Safety : A Guide to Inflating, Rotating, Balance & Alignment

The only thing between you and your family’s safety and the road, are the tires on your car.

All too often, car tires are an afterthought. We jump in our cars and whisk away to our destination, never considering the condition or current state of the vehicle’s tires. Tire condition, including tire air pressure, are critical to a car’s traction control, fuel economy, and safety of the vehicle.

In the 1990’s, over 100 people lost their lives due to tire blowouts resulting from the Ford Expedition and Firestone tire fiasco. While both companies took responsibility and corrected the problem, tire safety–regardless of brand and vehicle–remains an important vehicle component to be diligently maintained.

Underinflated and overloaded tires are the principal contributing factors to premature tire failure. The ability to steer, stop, and maintain traction in a vehicle with tires in either of these conditions, is severely compromised. Conversely, by properly maintaining and inspecting automotive tires for proper pressure, tread condition, signs of cuts or abrasions, and avoiding road hazards, tire problems are averted.

Recommended Tire Pressures and Load Ratings

These are found on the vehicle’s certification labels. Information included on the label are:

• Recommended tire size
• Cold tire inflation pressure
• Total vehicle capacity weight

Gross axle weight rating (GAWR) – the total weight for which the axles are designed for.

The label is attached to the driver’s side door edge or post, on the inside truck lid, or the glove compartment. The car owner’s manual also includes this information.

Tire pressure is measured in pounds per square inch (psi), or kilopascals (kPa), and indicates the amount of air in the tire. The vehicle’s recommended tire pressure rating is determined by the manufacturer’s engineers based on the type, weight, and class of vehicle calculates the recommended tire pressure. This rating is based on “cold inflation pressure”. In other words, the amount of pressure in the tires after the car or truck has been parked overnight.

The tire pressure indicated on the sidewall of tires is not the recommended tire pressure for the particular vehicle for which the tires are installed. The pressure rating found on the tire side wall is the maximum air pressure the tire should be inflated to–under normal operating conditions. It is a rating determined by the tire manufacturer regardless of the vehicle for which is it installed.

Tire tread is also crucial. Most passenger tire designs are for driving in all types of road conditions–like ice and rain. The tire treads provide a path for water to escape from beneath a tire during rainy conditions while providing improved grip on icy roadways.

Tires employ built-in wear indicators at the bottom of the treads. Raised grooves appear flush, or even, with the tire tread when the tires are worn to the point of requiring replacement. Tire tread worn down to 1/16-inch is the maximum allowable wear to passenger tires. A common tread wear check is to place a penny into the tread grooves, with Abe’s head facing down. If the top of Lincoln’s head is visible, the tread depth is below 1/16th of an inch.

Tire Balance and Alignment

Maintaining proper tire balance improves the car’s handling, as well as a smooth ride for the car’s occupants. If a vibration in the steering wheel occurs while driving, this could indicate an out-of-balance tire condition. A tire that is severely imbalanced, causes premature wear on the tire and creates a hazard for both the affected vehicle occupants and surrounding motorists. Tire rotation and balancing should be performed around 5000-mile intervals.

Tire Rotation

Rotating the tires at the manufacturer’s recommended intervals will extend the life of the tires. It also allows for all four tires to wear evenly. When all four tires are of equal size–and ideally they are–tires are rotated from front-to-back, and from side-to-side. In addition to allowing for even tire wear, tire rotation is an excellent opportunity for checking the tire/wheel balance.

Make a point of checking tire pressures and tire conditions at least once per month, as well as before extended road trips. Do not rely on the car’s tire pressure monitoring system to warn of an under-inflated tire, these systems only indicate a problem after the tire pressure drops by ¼ or more of the recommended tire pressure.

Tire damage suffered internally due to operating with low-air pressure cannot be corrected. Even after refilling the tire to its optimum tire pressure, the damage is done.