The Power King Towmax STR II is a premium radial ST tire for most trailer applications. It has a 5 rib circumferential tread pattern with full depth tread sipes for some additional grip on slick roads. The tire runs cooler than bias ply tires, which means longer wear-life. Radial tires on trailers also tend to deliver a little more shock absorption, and due to running cooler, better fuel economy. The Towmax STR II has additional nylon overlays in the 15 and 16 inch tire sizes to help deliver the additional load carrying capacity. This tire is popular with Tires-Easy customers and gets good reviews.