By Mary Jackson

Motor Matters

You may not know it, but your car’s tires may be trying to communicate with you. Really. Although they can’t talk, what they look like speaks volumes. So grab this newspaper and let’s head outside to spend some quality time with your tires.

Regularly checking your vehicle’s tires can save money, and even lives. Keeping them inflated to the manufacturer’s specifications will keep them from wearing faster, as even a small degree of underinflation (4 psi) can decrease a tire’s life by as much as 10 percent. As for safety, underinflation is the single largest reason for blowouts; plus, it can cause your car to take longer to stop.

Ready to commune with your tires? I’ll tell you what to look for, and what the different signs mean.

Underinflation: When a tire doesn’t have enough air, its sides sag and puff out, and its middle section pulls up and away from the pavement. Only a small portion of the tread makes contact with the road. Underinflated tires show wear on the edges.

Overinflation: When a tire has too much air, only its middle section touches the road surface. The tire’s sides pull up and away from the road and just a small amount of tread makes contact with the road. With overinflation, the tire shows excessive wear in the middle.

Tread wear on one side only: An irregular tread wear pattern on the tire – with more wear on one side than on the other – is often an indicator of alignment problems.

Tire is worn erratically: If a tire is worn erratically (this is a pattern referred to as cupping or scalloping), it may be that the wheel is out of balance, or the shock absorbers or ball joints may be worn.

The inflation and wear issue is tremendously important because the only connection between your car and the road are the tires – and the contact patches are no bigger than the size of your hand!

To provide the maximum surface for contacting the road, tires would have to be wide and smooth, with no grooves or indentations. Once grooves are made, the amount of tire touching the road is reduced. But tires must have grooves to provide drainage for water, mud, and snow so that secure contact with the road can be maintained.

How much groove – that is, what type of tread – do you need when you’re buying tires? It depends on the roads you drive on, and the weather in your part of the country. Conventional treads provide good traction on dry roads. All-season tires last longer than snow tires, and still do a reasonably good job of handling bad weather road conditions. If you live in an area where the average snow and ice accumulation is marginal, all-season tires can save you money by allowing you to have just one set of tires. If there’s no snow where you live, conventional tires are all you need.

As for more heavy-duty tires, the tread on mud and snow tires has especially deep grooves, which are specifically designed to dig down and make contact with the road below. This aggressive tread works well on ice and snow, but it wears faster on dry roads than a conventional tread does. Studded tires have metal studs embedded in them. While not legal in all states, they offer even more traction in the toughest of conditions.

No matter what type of tread you have, the grooves in tires can only push out so much water before they fill. In those instances – when they can’t push out all the water you’re driving through – a scary driving condition called hydroplaning can occur.

That’s when a layer of water forms between the tire and the road surface, causing the tires to lose contact with the road. No contact means no traction or control.

The best way to avoid hydroplaning is to have sufficient tread, the correct tire pressure, and to slow your car as you approach large puddles so the tires’ grooves have more time to do their work.

You need to check your tire’s air pressure and tread once a month. Skipping this simple five-minute check can be dangerous.

Be sure to have your tires rotated according to your manufacturer’s recommendation. And if you don’t want to take my advice, just look at your tires, they’ll show you.