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We Put Snow Tires on a Corvette and a Porsche to See How They Handle Snowy Roads

Car and Driver logo Car and Driver 2018-12-05 Daniel Pund
Can advances in traction aids and winter tires turn high-powered sports cars into year-round Snowbelt vehicles?© Marc Urbano Can advances in traction aids and winter tires turn high-powered sports cars into year-round Snowbelt vehicles?

To those of us who endure Michigan winters, with their coatings of dirty slush and skies the color of raw aluminum, the harbingers of spring are keenly cataloged. In grade school, we were taught to be on the lookout for the return of that prodigal son of the avian world, the robin. To the frostbit and vitamin D deficient, the presence of the orange-breasted bird inspires hope that light and warmth will indeed return eventually.

Birds are nice and all. But, for us, the ultimate sign of spring is catching sight of the year's first Corvette. Thirty years ago, nobody drove their Corvettes in the winter. Not in the upper Midwest, anyway. Nobody. No, winter was the season when you broke out the old Plymouth Volaré and mounted big gnarly snow tires on the rear (steering fidelity is a modern fascination).

But these days, well, most people still don't drive their Corvettes in snowy-region winters. But some do. A few. We do. For more than a decade, technology has been chipping away at the reasons to hibernate your sports car. Anti-lock brakes begat traction control, which begat stability control, which made better use of available traction. Concurrently, development of non-knobby, non-studded winter tires (you're not supposed to call them snow tires anymore, except that everyone in the Snowbelt still does) improved traction on snow and ice, increasing not just perform­ance, but comfort.

a close up of a yellow car© Marc Urbano

More recently, carmakers have been active participants in co-developing winter tires for their sports cars. Porsche offers several winter tires in varying sizes (and from various brands) for the 911 and the 718. You can order a Bridgestone Blizzak package from Aston Martin for your DB11. And in 2017, even McLaren got into the game, announcing factory-spec Pirelli MC Sottozero 3 tires for the 570 models.

McLaren couldn't make a 570S available on snow, er, winter tires for our test. So, we got a bright-yellow base 911 Carrera wearing 19-inch Porsche-spec Pirelli Winter Sottozero Serie II rubber. Next, we grabbed the key to our long-term Corvette Grand Sport, which was shod with absurdly wide Michelin Pilot Alpin PA4 winters, and headed north for 550 miles through periodic snow squalls to the city of Calumet in Michigan's Upper Peninsula. The area gets 200-plus inches of snow annually, an amount we reckoned was more than adequate for our winter-tire-testing purposes. There we would spend a full day at the Keweenaw Research Center (KRC) proving grounds evaluating our snowshoe-shod sports cars. Part of Michigan Technological University, KRC operates as a full-service test facility for a number of carmakers and their suppliers; it includes circle tracks, slippery grades, an ice rink, four snow-handling courses, and just some big flat expanses of whiteness.

© Marc Urbano

Our aim was to determine whether advances in traction aids and tire technology could make what was once unthinkable-i.e., driving a mega-horsepower sports car over the long, snowy haul-somehow reasonable. Our daylong trek to the proving grounds suggested that they could. Even on unplowed highway sections, traveling at extralegal speeds, we felt as comfortable and safe as we would driving one of the countless Chevy Tahoes we passed. Our low-slung sports cars, though, traveled directly in the slushy spray of the SUVs. Decent windshield wipers and a full tank of washer solvent meant that once free of the spray, our visibility was fine. By the time we hit the U.P., the Porsche had grown a most luxuriant dirty-slush beard.

Our first order of business was KRC's Handling Course No. 4, a 0.9-mile packed-snow serpent bordered by three-foot-tall walls of the white stuff. The 911, even without the company's all-wheel-drive system, felt right at home here. We completed a few familiarity laps with its stability- and traction-control systems fully engaged. While that is indeed the safest way around the course, it was also the slow and frustrating way. With 62 percent of its weight over the 295/35R-19 rear Sottozeros, the Porsche could put down a steady stream of torque through the snow. And despite its rearward weight bias, it handled neutrally, laying down smooth slides and carrying more speed through the corners than we initially thought possible. Its best lap of 1:28.5 was almost seven seconds quicker than the Corvette's. It averaged 37 mph, two higher than the Corvette, and touched 53 mph on the front straight, four higher than the more powerful Chevy. So good was the 911 around the snow course that we returned to the handling track when the rest of our testing was done and ran laps in it until KRC closed at dusk.

© Marc Urbano

The Corvette Grand Sport was an altogether trickier thing to usher around the course. We scrolled through the various layers of Chevy's Perform­ance Traction Management system, trying progressively more-permissive settings, but regardless of mode, we could not coax the Corvette to 911-challenging times. With all systems off, the Vette turned its best lap of 1:35.2 with an average speed of 35 mph and a top speed of 49. The Michelin Pilot Alpin PA4 is a fine tire, but the Grand Sport's steamroller-width rears (335/25R-20) were not able to put the power to the powder. The lower top speed is due to the careful throttle application required to keep the car in line exiting the final icy bend before the front straight. The Corvette desperately wanted to rotate, and taking a lap in it required constant vigilance to steering and throttle inputs. And while we don't anticipate owners will be running laps around snow courses, the behavior there is applicable to road manners. Maybe there's a reason that, even now, most Corvette owners garage their cars in the winter. According to TireRack, of all the tires it sold in the past year for C5 through C7 Corvettes, only 1 percent were winters. The company sells about six times as many winter tires for 911s. Also, Chevy didn't co-develop the Alpin PA4 with Michelin. But it is the winter tire it recommends for the car.

The Corvette's performance on our snow-braking and snow-skidpad tests implicate the Michelins. In 40-to-zero-mph braking, the Corvette's 213-foot stop trails the 911's impressive 169-foot performance by 26 percent. Likewise, the Corvette could post only 0.25 g on the skidpad to the 911's 0.28 g. Once we returned to dry pavement by our Ann Arbor headquarters, we ran the cars through the same braking and skidpad tests while wearing both their winter and summer tires. In the dry, where its big footprint was an advantage and not a detriment, the Corvette stopped in slightly shorter distances from 40 mph (53 feet on winters and 41 feet on summer tires) than did the 911 (56 feet on winters and 43 feet on summers).

a car covered in snow: The 911’s rear weight bias helps it put power down. Want more winter capability? Then order the all-wheel-drive Carrera 4 version of the car. The Corvette Grand Sport is a primo snow thrower. Occasionally, its prow will dig into fresh snow and send a bow wave of powder over the top of the car.© Marc Urbano The 911’s rear weight bias helps it put power down. Want more winter capability? Then order the all-wheel-drive Carrera 4 version of the car. The Corvette Grand Sport is a primo snow thrower. Occasionally, its prow will dig into fresh snow and send a bow wave of powder over the top of the car.

Also, near the end of our roughly 20-degree test day, the Corvette's front-left caliper froze solid to the rotor. In fairness, we did repeatedly wash the cars before entering the test facility so as not to drag road salt onto the pristine surfaces. As we started towing the car to an on-site garage, we heard a loud kaboing from the front as the brake pads gave up their icy grip. The Porsche, which we washed the same number of times, had no such problem.

It's no surprise that our sports cars were hobbled by the snow; all vehicles are. But the benefits that sports cars bring to the dry pavement-handling balance, ready power, proper steering-also apply in the winter. They're still more fun to drive than a regular car, even in a low-mu environment. That's particularly true of the Porsche. But old habits die hard and, as the numbers suggest, only the most dedicated of drivers will fit winter tires to their sports cars. Most likely, the arrival of the first Corvette in spring will remain a reliable harbinger for some years to come. 

From the December 2018 issue

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