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Terms of Endearment: How to Read the Sidewall on a UHP Tire

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Terms of Endearment: How to Read the Sidewall on a UHP Tire

It seems the information on the side of a tire increases as the tire’s profile decreases. Should you need to explain to your customers — or new hires — what it all means, the tire illustration below will tell them almost everything they need to know.

Although they can appear together, the M+S symbol is much more common on an ultra-high performance tire than the mountain snowflake symbol because their definitions are based on very different criteria.

When a tire has an M+S (or M&S) symbol, it has superior starting, stopping and driving performance in snow conditions than non-M+S tires do, according to the Rubber Manufacturers Association (RMA). The RMA standard is based on a geometric tread pattern definition.

“The M+S designation was first used to differentiate the knobby, bias-ply tires intended for use on muddy and/or snow-covered roads from the straight rib tires used on early cars or trucks,” says TR Wholesale Solutions. “When early radial-ply tires were also found to deliver more snow traction than the straight rib, bias-ply tires, the tire companies introduced all-season tires.”

Deciding its M+S definition was not enough to differentiate an all-season tire from a true winter tire, the RMA and Rubber Association of Canada agreed on a performance-based standard for winter tires in 1999. They created the mountain snowflake pictograph to identify tires designed for use in severe snow conditions.

The mountain snowflake sidewall symbol is always placed adjacent to the M+S designation.   ■ 



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