Doctor's Review: Medicine on the Move

October 18, 2017
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Get A Grip

This winter, steer clear of trouble with today's hi-tech snow tires

Remember when snow tires looked like they were more suited for a demolition derby than actual paved roads? They had big knobby treads -- at times with protruding metal studs -- that hummed in your ear while you cruised down the pike. They not only worsened highway noise but also ate away at your driveway.

That all changed during the '80s when tire companies created the all-season tire. For the most part -- like the family station-wagon after the introduction of the mini-van -- the snow tire was gone from our roads. At last, we had a tire that could be used year-round without the hassle of having to be changed every winter and spring. Unfortunately, it was too good to be true.

While the nomenclature of an all-season tire holds partially true, it is nonetheless a compromise. All-season tires do not give the optimum performance of a dedicated summer tire, nor do they perform as well as a true snow tire. They were also created primarily for regions that receive moderate levels of snow, in both frequency and amount, and were not designed for mobility in heavy snowfall areas. Undoubtedly, the changeover factor was foremost in everyone's mind, and the primary reason for the all-season tire's success. Noise, handling and comfort were usually at the bottom of everyone's list, and caused considerable apprehension about switching to dedicated snow tires.

Everything changed again in the '90s. With automobiles becoming increasingly sophisticated in handling, braking and steering, and the onslaught of mini-vans and SUVs, tire technology needed to keep up with the modern automobile. The tire industry responded to the challenge, and snow-tire technology has risen by leaps and bounds. This has been due, in part, to Europe's mandatory use of dedicated snow tires.

HOW TO READ DESIGNATED TIRES
But tires -- be they rain, high-performance, all-season, snow or run-flats -- are possibly the most abused, ignored and misunderstood part of our cars. Lessons are needed to teach motorists how to read the tire's designations. For starters, let's begin with the tire markings found on the sidewalls. A typical tire might read 225/55R-15 92V. The R identifies this as a radial tire as opposed to the once-popular bias-belted variety. It has a nominal width of 225 millimetres from sidewall to sidewall. Its aspect ratio, or profile, of 55 specifies that this particular tire's section height is about 124 millimetres (55 percent of 225). The tire is mounted on a 15-inch (43-centimetre) diameter wheel, and its speed rating is V, good for 250 kilometres per hour. The 92V load index translates into a carrying capacity of 1389 pounds (approximately 630 kilograms).

Some manufacturers add the letter P, as in P225/55R-15, to indicate that this is a passenger car tire. In addition, you'll find information on the tire's ability to dissipate heat. This information is shown as the tire's temperature grading: A, B or C (where A is the best and C the worst). Most snow tires rate a B. Tires also have markings for treadwear ratings. Unfortunately, all manufacturers have their own criteria on how to perform and rate such testing, and these results suffer from a lack of reliable standard.

CONFUSED READINGS
Finally, we come to the M+S designation (as in mud and snow), or the most confused aspect of tire readings. In the not-too-distant past, the M+S designation meant the tire was a dedicated snow tire. Somewhere along the way, however, many tire-manufacturers began adapting the M+S for all-season tires. This created widespread confusion until the government stepped in and forced tire companies to clean up their act. As of last February, a new category was set up which led to a proper snow-tire being defined as a tire "for use in severe snow conditions." Tires meeting the government's new criteria now wear a mountain/snowflake pictograph next to their M+S designation. The new designation is being adopted worldwide.

Like many of you, I had been driving on all-season rubber for most of the '90s. With front-wheel-drive disc brakes and all-season radials, I felt much more confident than with the cars I used to drive decades ago (rear drive, drum brakes and big knobby bias-belted snow tires). Front-wheel-drive makes plowing through the white stuff so much easier, so why go through the hassle of changing to winter tires? Why all the hype about snow tires when we've all become accustomed to driving with the all-season variety?

THE TRUTH IS GRIPPING
I found out the answer after I made the switch last year, when I chose to go with "ice" radials, the latest in winter-tire technology. The results were astounding from the beginning. From accelerating to cruising and stopping, the car felt like a totally new vehicle. The first of many rewards came just days later when a car spun out of control directly in front of me. I negotiated around the vehicle in perfect control, but others behind me were in the same embarrassing predicament as the car in front.

So what has happened to winter rubber over the last decade? The simple yet correct answer is technology. Let me illustrate with Goodyear's Ultra Grip Ice, a standard winter tire. The Ultra Grip Ice's tread is composed not only from carbon-black polymers (polymers define a tire's performance characteristics), but also from several other polymers as well as a silica compound. Silica allows the tire to perform better at extremely low temperatures and enhances wet traction. According to Goodyear, the tire's performance increases as the temperature decreases. In addition, the Ultra Grip Ice contains a combination of carefully placed blades and sipes, which are tiny slits that enhance a tread pattern's controlled flexibility and microgrip, and help evacuate the film of icy water lying just beneath the snow. Goodyear claims that the Ultra Grip Ice delivers 25 percent better traction than a conventional snow tire, which is 25 percent better than an all-season tire.

 

TIRE ANECDOTES
Bridgestone's Blizzak, one of the forerunners of this technology, looks more like a conventional all-season tire than a winter tire. And it is, except that it has a layer of gummy multicells (hundreds of thousands of tiny indentations that bite the snow). While the Goodyear remains a snow tire throughout its life span, the Blizzak reverts to an all-season tire once the multicells wear out. It is an interesting formula that guarantees you are well-protected in severe winter conditions for several years (depending on your mileage, snowfall and general care) before leaving you with an all-season tire.

Like the Goodyear, Pirelli's Winter Ice also features high silica content, and retains its winter qualities. Unlike its competitors, Pirelli offers two tread designs: a directional tread design for smaller cars, and an asymmetrical design for medium and large vehicles. Both tires have a speed rating of Q, which is good for speeds not exceeding 160 kilometres per hour.

The magic formula for ice radials is a compound one. Tread design is effective, but only up to a point. The adhesion capacity of the tread compound, as well as the effect of the sipes, play a big role in a tire's ability to perform in winter. One formula worth remembering is that snow grips better to snow (remember making those big, rolling snowballs when you were young?). Like the Goodyear, the Blizzak sheds the tiny water molecules, trapping only the snow in the sipes. A hotter running tire would melt the snow on contact and offer far less traction. While studded tires still offer marginally better braking on ice, ice radials outperform studded snow tires in every other aspect. According to Pirelli, only the sipes and the tire's adhesion capacity matter on sheer ice, so tread design is less important here than on fresh or packed snow.

Michelin, a company that has produced tires for vehicles ranging in size from bicycles to the space shuttle, introduced the Pilot Alpin to complement its Arctic Alpin winter ice radial (a tire Michelin claims brakes better than studded snow tires). The Pilot Alpin is Michelin's first high performance winter tire and features an H speed rating (200 kilometres per hour). Clearly, not all regions in Canada require the grip of ice radials, so not all technology is limited to ice radials. Michelin's XM+S Alpin has innovative "Y" shaped sipes that double as the tread wears down (doubling the number of sipes when the tread reaches near the half-way mark).

In the end, it becomes apparent that snow tires are a vital part of a car's survival in Canadian winters, like coats, hats, gloves and boots are for the human body. Motorists living in regions like Toronto and Calgary -- where snowstorms are usually followed by a thaw -- should still opt for dedicated snow tires. Considering that a tire's footprint is about the size of your palm, every edge you get to enhance winter traction can't be ignored. The benefits of dedicated snow tires far outweigh the cost of changeovers.

CHOOSING THE RIGHT TIRE
Of course, all this talk begs a very interesting question: Which snow tire is the best? There is no simple answer. I once had a set of tires that performed wonderfully on surfaces as diverse as unpaved country roads and highways, but proved unnerving on a local steel-graded bridge. Diverse factors such as suspension design, driving habits and road conditions play a big part in tire operation. Also, what works best on a Ford Taurus may not necessarily be effective on a Chevrolet Malibu. The best way to find out what is best for your car is to ask advice from a tire retailer that carries a number of brands.

It's obvious that today's snow tires are ages ahead of those offered years ago. They provide excellent traction, and a comfortable, quiet ride. Who would have thought that tires with tiny sipes would offer more grip and control than those big knobby tires of yesteryear?

FINAL ADVICE
Still not convinced? Tire companies are so confident in their product that they're providing attractive bonus packages to entice customers. Uniroyal, for example, is offering those who purchase Tiger Paw Ice and Snow tires one free tow in the event their engines proves less reliable than their tires.

Remember, though, to purchase four snow tires and not two. It's almost safer to stay with four all-season tires than with a two-and-two set-up. In order to beat the high cost of mounting, balancing and remounting your tires with each change of seasons, pick up an extra set of rims at the local car junkyard (auto recycling centre these days). You'll not only be able to replace the downsized spare with one of the all-season tires, but you'll only have to exchange wheels. This simple technique saves money and hassles in the long run. It's also a good idea to check tire pressure the day after you've had your tires installed since the ambient temperature outside and the temperature of the air inside the heated garage may vary.

Safe motoring to everyone!

 

This article was accurate when it was published. Please confirm rates and details directly with the companies in question.

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