A Google search showed that both styles are available with Performance having the RT800 in the full range of sizes. Looking at photos on Performance's and Bike Tires Direct's websites and their descriptions it appears the only difference is the design of the arms connecting the spider to the brake track. The RT800 arms are straight and the CL800 has curved arms which they claim are..... "more robust leading to quieter operation." So, yes the CL800 is a direct substitute.