Schwalbe thunder burt evo mtb tyrethe tire development goal was to combine the best of racing ralph and furious fred at less than 400g the weight is almost exactly in the middle with its many small lugs thunder burt is close on the heels of racing ralph regarding grip and in terms of rolling resistance its even better than furious fred features liteskinskin tires have light thin sidewalls advantages weight saving and reduced rolling resistance size etrto 54 622 29 x 210 inch type f