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Treading Softly Where the Rubber Meets the Road

Caring for Your Tires

by Jim Bray

It could be time to think about retiring.

Retiring your car, of course. Your "nest egg" notwithstanding, it’s important to know when your vehicle’s rubber has been rubbed out. Your tires, after all, form the all-important bond between the tons of metal and material that you drive and the asphalt on which you drive it.

But it’s an asphalt jungle out there, with terms like “Z rated,” “60 series,” “Run Flat,” and others - as well as conflicting data that tells us bald tires are unsafe, while racers use them all the time.

Talk about a tiring subject!

Tires are surprisingly complex beasties. They start with a rubber-coated steel loop, the Bead Bundle, that keeps the tire seated on the wheel rim. The Body consists of fabric “plies”(layers), which in a radial tire run at 90 degrees to the tread. Belts, as in “steel belted” provide puncture resistance and help the tread stay as flat on the road as possible. The Sidewall, the part you see when you admire a nice set of wheels, protects the body and provides sideways stability so your vehicle doesn’t flop over the first time you hit a tight corner.

Then there’s the tread, but before it’s added, the pieces are assembled into a “green tire” and then everything’s bonded together (called “Vulcanizing”) while the tread pattern and that fancy side lettering are molded in.

Presto! A brand new tire!

Different tread patterns offer maximum traction, depending on the tire, for pavement, dirt, mud and snow, rain, etc. Choosing which tire’s best for your vehicle depends on what you drive and where you drive it. “You have to make some compromises,” says Scott Wilson, Manager of Advocacy and Community Services for the Alberta Motor Association. “If you do a lot of city driving, with only occasional highway driving, you can probably get away with a good all season tire, but in rural areas you might need an actual snow tire for the winter. You can even take it so far as to look at some specialized ice tires.”

Wilson warns about tradeoffs, however. “All season tires work pretty well, but a good snow tire is actually much better for winter driving. You have to keep in mind, though, that if you keep (winter tires) on in the summer your vehicle won’t handle as well or ride as smoothly, and it’ll be a lot noisier.” Summer-driven winter tires also wear much more quickly, he says.

Besides “garden variety” all season tires there are also All Season M&S (mud and snow) tires, Light Truck & SUV Off-Road, All-Terrain Tires - and variations.

Run Flat tires allow you to drive for a short distance even if the tire deflates, while temporary spares, as the name screams out, “Are only meant to get you to the nearest garage,” says Wilson.

Choosing the correct rubber for your lifestyle also means taking into account tire size and configuration. This is where those numbers and letters on the sidewall come in (see below), and it’s important to match the tire to the vehicle.

Buying tires is only the first step: you also need to take care of them which, according to the AMA’s Wilson, isn’t a priority with many drivers. “Most people don’t even check their tires’ pressure,” he says, pointing out that all your tires - including the spare - should be checked once a month, while the tires are cold. Wilson recommends buying an inexpensive tire gauge, which he says are far more accurate than the ones at the local garage, and to keep it in the car at all times.

According to Doug Paulgaard, owner/manager of Fountain Tire in High River, tires should be rotated “Every 8-10,000 km to help ensure even tread wear.” His advice is to have the tires inspected during rotation, and to ensure there’s enough tread left. “If there’s only 2/32 inch of rubber left,” he says, “A wear indicator shows a solid bar across the tread. If you see that, it’s time to replace the tire.”

Which begs the question “Why do race cars use bald tires?”

Rick Coutts, Chief Driving Instructor for the Western Canada Motorsports Association, says “It comes down to optimizing grip, which depends on two things: the load pressing the tire into the track, and the surface area of the rubber contacting the pavement.” The racing slick, Coutts says, has more rubber touching the road than a similarly-sized treaded tire. “Since racers are concerned with the maximum possible grip a slick tire is the tire of choice.”

This changes once there’s significant water on the track, however, which is why racers switch to treaded tires - or quit racing altogether - when it rains.

So treaded tires are actually a compromise between ultimate “stick” and being able to control the vehicle in the real world, where you have to deal with changing weather conditions.

Besides rotating the tires at 8-10,000 km intervals, you should have them rotated at the first sign of irregular wear. Tires should also be balanced to minimize vibration and avoid steering and suspension damage. And proper alignment ensures the tires are actually heading where you want them to, so avoid scuffing against curbs because that can throw out your wheels’ alignment.

Visually inspect your tires frequently, and remove stones, glass and other stuff from the tread to prevent damage and/or leaks.

As the slogan says, there’s a lot riding on your tires, so making sure yours are properly maintained is absolutely vital when the rubber meets the road.

Understanding Your Tires:

“P225/50 R 16 92 V”
“P” indicates a passenger vehicle tire (“LT” = Light Truck and “T” = temporary). The next number (225) is the width in millimeters from sidewall to sidewall. Then comes the “aspect ratio” (50), the height from the bead to the top of the tread, as a percentage of the width (a 50 series tire is half as tall as it is wide: the lower the number, the “lower profile” the tire).

Next comes tire construction: “R” means radial, today’s most common. Then comes the wheel rim size (16), in inches. Load Rating (92) indicates how much weight the tire can safely carry; the higher the number the greater the load.

The Speed Rating (V), tells you how much of an “accelerating experience” you can expect. Maximums range from a low of 50 km/h (“B” rating) to a high (“Y”) of 300 km/h.

So our P225/50 R 16 92 V tire is a passenger vehicle radial tire that’s 225 mm wide, half as tall, fits 16 inch rims, can carry up to 630 kilograms and (if you can get away with it), is safe up to 240 km/h (the tire, not necessarily the driver or vehicle!).

Not all manufacturers include the “tire type” on the vehicle, but your dealer can help if you aren’t sure.

There are other indicators as well, for example the “Uniform Tire Quality Grade System” but you don’t need to be as up on that particular knowledge unless you’re really doing your homework.


Jim Bray is a member of the Automobile Journalists Association of Canada. His columns are available through the TechnoFile Syndicate.

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