Winter tires increase fatal accident risk in summer, Swedish study finds

A study conducted by VTI, Folksam, and the Tire Industry Information Council, in collaboration with Trafikverket, has found a significant increase in the risk of fatal accidents when using winter tires during the summer months.

Analyzing 725 fatal passenger car accidents in Sweden occurring between May and September from 2012 to 2021, researchers found that vehicles with at least one winter tire were heavily overrepresented. While winter tires are estimated to be on approximately seven percent of Swedish passenger cars during summer, they were present on 22 percent of the vehicles involved in the studied fatal accidents.

The researchers attribute this to the inferior road grip provided by winter tires on dry or wet asphalt in higher temperatures. Previous testing indicates that braking distances can be 20 to 40 percent longer compared to summer tires. The increased risk remained significant even when accounting for older vehicles lacking electronic stability control (ESC) and when drivers were not under the influence of alcohol or drugs.