Winter tires keep cars going —and whoa-ing — in snow

John McCormick
Special to The Detroit News

Crested Butte, Colorado

Put a rear-drive sports car on a snow-covered course and normally the result is lots of wheel spin and little progress. Mazda, however, showed its MX-5 roadster can be plenty of fun to drive even when grip levels are minimal.

At an ice-driving course set up in a field blanketed in several feet of snow near Crested Butte in the Colorado Rockies, the MX-5 was one of several new Mazda models to demonstrate that winter driving does not have to be a white-knuckle experience.

Although most MX-5 owners are unlikely to subject their cars to such extreme conditions, the point of the exercise was to show that with proper winter tires — Bridgestone Blizzaks in this case — the near impossible becomes feasible.

In the case of the CX-3 and CX-5, Mazda’s compact and midsize crossovers, negotiating the icy course was even more straightforward, as the two models were equipped with the Japanese automaker’s sophisticated “predictive” all-wheel drive system. (The same system is also fitted to Mazda’s upcoming CX-9 large crossover.) Combined with the remarkable grip provided by the Blizzak rubber, the predictive system gives the Mazda crossovers better performance in icy conditions than several competitors, including the Honda CR-V, Subaru Forester and Toyota RAV4.

The Mazda’s advantage is based on its so-called i-ACTIV all-wheel-drive control system. The system analyzes inputs such as road speed, engine and transmission speeds; weather conditions via windshield wiper use, and internal and external temperature sensors; plus the vehicle’s dynamic condition via yaw sensors and steering wheel position. All these conditions are analyzed more than 200 times per second to determine the amount of torque to transfer to the rear wheels.

“Our system anticipates front tire slip and applies just enough rear-wheel torque to prevent slip from occurring in the first place,” explains Dave Coleman, Mazda North America development engineer.

By contrast, most rival all-wheel-drive systems are reactive, redirecting torque only after wheel slippage is detected, rather than anticipating the need. For the driver, the difference in the two competing approaches to all-wheel drive technology can appear subtle or fairly dramatic, depending on the severity of road conditions. But when the going gets rough, there’s no question that the Mazda technology gives a better sense of control and smoother responses to steering and throttle inputs.

In back-to-back testing at Mazda’s Crested Butte track it also became clear that all-season tires are no match for winter tires when it comes to finding traction on snowy or icy roads. Even more importantly, winter tires give far superior stopping capability in low-grip conditions, a fact that could make the difference between a near miss and a collision.

Most of the major tire companies, including Michelin, Goodyear and Continental, produce excellent winter tires, but Bridgestone’s Blizzak brand has established an outstanding reputation.

“Winter tires are built specially to give drivers better grip, stopping power and more control in snow, slush and ice,” said Bridgestone spokesman Chris Welty. “The thin layer of water on the road from ice or melting snow can be very dangerous, and winter tires are designed to clear that icy water and grip the road.”

One question often raised by drivers interested in using winter tires is when to make the switch. “You shouldn’t wait until the snow falls,” said Welty. “Change over when it’s cold enough to see your breath.”

The bottom line for Michigan motorists facing at least another month of winter: It’s not too late to make sure you have the best chance of surviving the next wave of nasty weather by fitting winter tires. And if you’re shopping for a crossover vehicle, keep in mind that Mazda engineers have gone the extra mile to make their vehicles cope with the very worst Mother Nature can deliver.

John McCormick is a columnist for Autos Consumer and can be reached at