Correct Tire Pressure

Correct Tire Pressure

Proper tire pressure is critical for safe driving and fuel efficiency, but many passenger and light truck vehicles operate with under or over-inflated tires. Ninety-five per cent (95%) of a vehicle's weight is supported by the tire air pressure, with the tire supporting just 5%, making inflation a critical part of a tire's ability to perform. Tire inflation also has a strong impact on tread life.
Relying on a sight inspection alone is not an accurate way to measure tire pressure. Tires may be significantly under or over-inflated, yet you may not be able to tell just by looking at them.
The only accurate way to know if your tires need to be inflated is by measuring their pressure with a reliable tire gauge. Tire gauges are available at most automotive supply and hardware stores.

Correct Tire Pressure

Correct tire pressure varies from vehicle to vehicle and wheel to wheel. In fact, the recommended pressure for personal vehicles ranges from 20 to over 50 psi.

The correct tire pressure for your vehicle is listed on the information placard. This placard is normally located on the edge of one of the doors, the inside post of one of vehicle's doors or inside the glove compartment, trunk, or fuel door. Your owner's manual should include the correct tire pressure or direct you to the placard's location on your vehicle.

The pressure listed on the tire sidewall is the maximum tire pressure - or the tire pressure that is required to carry the maximum load of the tire. It is not the manufacturer's recommended tire pressure, which is a common misperception.

Under-inflation

Under-inflation is the leading cause of tire failure. Twenty-three per cent (23%) of vehicles have at least one tire under-inflated by more than 20%. Under-inflated tires on your vehicle lead to poor or delayed braking, steering and acceleration. Under-inflated tires may squeal when stopping or cornering even at moderate speeds, particularly on warm pavement.
 

The Effects of Under Inflation on Tire Wear and Fuel Use
Percentage of
Under Inflation
Percentage
Wear Increase
Fuel Use Increase
10% 5% 2%
20% 16% 4%
30% 33% 6%
40% 57% 8%
50% 78% 10%

Operating a vehicle with just one tire under-inflated by 20% (8psi) can reduce the life of the tire by 15,000 km and can increase the vehicle's fuel consumption by 4%. Without enough air, the sides of a tire bend and flex too much. This builds up heat, which can cause serious damage and leads to sudden tire failure. It will also increase rolling resistance, which reduces tread life and increases fuel consumption.

Over-inflation

Over-inflation can be a problem too. An over-inflated tire rides on just the centre portion of the tread. The smaller contact area means reduced grip on the road, leading to a harsh ride, handling issues (such as steering and stopping problems) and increased wear on tires and suspension components. Seventeen per cent (17%) of vehicles in Canada have at least one tire that is over-inflated by 20%.