WASHINGTON—North American tire makers have agreed on a voluntary, performance-based standard to differentiate snow tires from all-season tires. Tire manufacturing members of the Rubber Manufacturers Association and the Rubber Association of Canada announced the new definition for passenger and light truck tires Feb. 1.
A new sidewall symbol of a mountain with a snowflake inside will denote tires designed for performance in severe snow conditions, said Steven Butcher, RMA vice president of technical and standards.
That symbol will be in addition to the ``M&S'' (mud and snow) symbols already used on snow and all-season tires, he said.
The RMA and RAC worked on the new definition for about 2 1/2 years, after Transport Canada (Canada's counterpart to the U.S. Department of Transportation) requested it, Mr. Butcher said.
Whereas the M&S definition is geometric-based, the new snow tire definition covers tires that attain a traction index equal to or greater than 110 during the F-1805 snow traction test devised by the American Society for Testing and Materials.
``The ASTM test procedure is the best available right now,'' Mr. Butcher said. ``That doesn't mean it won't evolve further.''
Transport Canada is pleased with the results, according to Transport Minister David Collenette.
``This new standard will ensure that Canadian consumers can identify and purchase tires designed to provide a higher level of traction in Canada's harsh winter conditions.'' he said.
Standard F-1805 spells out how to set up ice and snow surfaces—including precise definitions of four types of snow—and how to conduct the test. The traction index is derived by measuring wheel slippage of the driven wheel vs. that of the non-driven wheel.
Each test consists of 10 runs over the prepared course, with traction values determined by averaging eight valid test runs out of 10, according to the ASTM standard. Each candidate tire is to be tested at least three times, preferably on different days.
Michelin North America and Goodyear both support the standard. Goodyear said it will start immediately to place the new symbol on its Ultra Grip line of winter tires.
The tire makers will test their winter tire lines over the next two years to determine which ones meet the new standard, the RMA said. The association expects full implementation of the snow tire symbol by the winter of 2000-2001, although some tire firms may follow Goodyear's lead and start using it later this year.