Continental Dubnital Tire - 29 x 2.40 Tubeless Folding BLK Grip Trail Casing E25Continental Dubnital Tire 29 x 2. 40 Tubeless Folding Black Grip Trail Casing E25. The Dubnital tire is designed for dry to damp conditions and for rocky hardpack and medium loose soils. Master the challenges of modern cross country and down country riding at speed. Dubnital supersedes its predecessor the championed Race King and takes performance to the next level. The master of speed tire ideal for hardpack terrain Hookless compatible Tubeless ready