Tyre Grip "helps keep you on the road regardless of the road conditions." You spray it on tires and get up to 50 miles per application. It costs $19.95. A second product, AutoSock, is a cloth-and-mesh cover you slip over a tire and wheel. It's "a quick and easy alternative to metal chains when driving on slippery roads." We paid $99 per pair.
We sprayed Tyre Grip on the tread of a Honda Accord's front drive wheels, then drove on a snowy Vermont road. We also drove up a small, snowy hill with the Accord's all-season tires alone, with Tyre Grip, and with AutoSocks over the front wheels.
Don't toss your snow tires. Tyre Grip improved traction modestly during acceleration and braking, but any benefit waned after about a mile. The Accord couldn't reach our hilltop with or without Tyre Grip. With AutoSocks, however, the car made it uphill many times. The downside: AutoSocks are cumbersome to put on and are meant to be used only on snow or ice and to be removed right away when the roads clear.