The Roadian AT Pro RA8 is comprised of a zig-zag sipe design and an open outside shoulder design to improve off-road performance with optimal mud extraction and heat reduction. The sipe-in-groove design prevents pebbles from getting stuck and improves mud extraction performance, while the multi-sequence tread design on the center and shoulder deliver optimal noise, wear and drainage performance. All sizes are Three-Peak Mountain Snowflake certified (excludes OEM, Flotation, and some sizes).