Roadstone N Fera RU1 – 235/55R18 (100V). Roadstone N Fera RU1 – Fantastic Driving With a fantastic ride and superb steering, your driving experience will be raised to the next level. One narrow groove on out-side is applied to increase the block stiffness and thereby improve handling and steering stability during cornering. 4G optimized compound technology delivers an optimized tread grip on both wet and dry surfaces.N’Fera RU1’s excellent wet braking performance is achieved with POS & HES technology. Optimal contact patch on road surface is realized by POS & FOS technology delivering best-in-class dry handling performance.