The WinterContact SI (Snow and Ice) is Continental's Studless Ice & Snow winter / snow tire developed for the drivers of coupes, sedans, minivans and crossover vehicles. Designed to operate in slippery wintry weather conditions, WinterContact SI tires enhance traction on cold, wet, snow-covered and icy roads.Featuring PolarPlus Technology, WinterContact SI tires use Continental's +Silane additives to offer a significant improvement in grip over summer tires by allowing the tread compound to stay pliable when temperatures consistently fall below 45 degrees Fahrenheit. The compound is molded into a directional tread design that blends dry road handling with foul-weather traction. High-density multi-angled zigzag sipes increase the number of the tread surface's snow biting edges to enhance wet road and wintertime traction while Traction Groove Technology base-of-the-groove ridges provide additional 3-dimensional snow-biting edges to improve braking traction in deep snow.WinterContact SI tires meet the industry's severe snow service requirements and are branded with the three-peak mountain snowflake (3PMSF) symbol.When the WinterContact SI is approximately 50 percent worn, a winter tread depth indicator molded into the tread design lets the driver know that the remaining tread is reaching the end of its ability to provide beneficial snow traction.Install WinterContact SI tires in sets of four only.Due to the traction capabilities of the WinterContact SI, Continental recommends using WinterContact SI only in sets of four to provide the best handling characteristics and tire performance.Winter tires are not UTQG rated. Related Information: What is the three-peak mountain snowflake symbol (3PMSF)?