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.
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.
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.
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).
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.