STI Black Diamond Radial ATR Tire (23x8-12) STI Tire & Wheel has now released a new diamond in the rough: Black Diamond. This super-versatile new ATV / UTV tire is designed to deliver crossover performance - an ideal choice for all terrain types and all seasons - at a value price. The Black Diamond's innovative "V" tread pattern bridges the gap between soft mud / snow / sand and hardpack surface capabilities. Its unique over-center tread elements provide a smooth, controlled ride on hardpack, while offering excellent traction and clean-out in soft conditions. The Black Diamond's 6-ply radial carcass was developed specifically to provide the stability needed for side-by-side UTV applications, while retaining the plush ride characteristics favored by ATV riders.