Higher tire pressure could save your life

By Barry Lake

In terms of safety, tires are among the most important items on a car.

It doesn't matter how well you drive, nor how good the steering and brakes on your car are if the tires have no grip on the road.

A tire for a modern car has many functions. It has to provide a smooth ride over uneven surfaces, it has to be puncture resistant, and offer good grip in emergency braking and cornering situations on all types of surfaces and in all types of weather.

There are other minor factors like road noise and durability that also have to be considered.

Not surprisingly, not even the best tires can excel at all of these things. And lower quality, cheap tires often don't rate highly on any scale except for, perhaps, the cost per mile factor. Sometimes they don't even measure up on that.

Generally speaking, good quality tires will cost you more but they usually pay big dividends in reliability, durability and, above all, safety.

A car's ability to stay on the road while cornering, and the stopping distance required in an emergency are both dependent on the amount of grip a tire produces.

This can depend on a number of factors including carcass construction, tread pattern and the rubber compound used.

It also depends on how much air you have in the tires. Neglecting your tire pressures can lead to disaster. An under- inflated tire is more prone to puncturing due to sharp objects piercing the now-baggy wall of the tire.

A tire with insufficient pressure will flex more in normal usage and generate high temperatures which make it even more prone to punctures, blow-outs and excessive wear.

And a tire lacking air has greatly reduced grip in cornering and especially in braking.

When the brakes are applied on a motor vehicle, weight transfers to the front of the car, pressing down on the front tires. If the tires are underinflated, the added weight balloons the walls outwards and this distorts the tire carcass so that the middle part of the tread curves upwards away from the road surface.

The tire then contacts the road only on the two outer edges, reducing the amount of rubber on the road, and the total grip of the tire, by a huge percentage.

So it is important, not only to keep your tires inflated to the pressures recommended by the manufacturer of the car (usually found on a placard inside a door jamb or inside the glovebox, and usually repeated in the owner's handbook) but to consider running them a few pounds per square inch higher.

Manufacturers mostly err on the side of having tires too soft, the reason being that it is important to them, and to the dealers selling their cars, that the car gives a nice, soft, quiet ride.

As a minimum, use the pressures recommended for sustained high-speed driving for your normal motoring. You can even try a little higher, depending on what degree of ride comfort you desire.

Increasing the tire pressures robs you of some ride comfort, but the pay-off is in reduced stopping distances, better cornering, longer tread wear and improved puncture resistance.