Abstract Tire wear particles (TWPs) are prevalent microplastic particles in the atmosphere and pose significant environmental and health risks to humans. Here, we investigated the ice nucleation activity (INA) of TWPs under mixed‐phase cloud conditions (∼−20.0°C < T < −5.0°C) and its changes caused by different environmental exposures, including UV and high temperatures (75.0°C). Ice‐active sites per mass of TWPs are about one to two orders of magnitude higher than those of other microplastics. Environmental exposure moderately reduces TWPs’ INA, attributed to modifications in surface ice‐nucleation sites, such as decreases in SiO2 signals. As the most abundant microplastics in the atmosphere, TWPs significantly contribute to global ice‐nucleating particles (INPs), particularly in North America, Southeast Asia, and Europe. Given that TWP emissions are expected to increase with the predicted rise in vehicle numbers, addressing TWPs’ impacts on cloud microphysical properties becomes increasingly imperative.