Originally Posted by chicky03

I haven't done much testing in 17,5 in a long time but most guys run the yellow/black combo because it has less grip and makes the car run a little more free. Less steering and less rear grip. If the track has low grip the pink/magenta family could certainly be faster, I have even seen it at big races but it is less common.

My personal experience with 13.5 and faster is the yellow family just does not have the traction the pink/magenta family of rubber does. The yellow rears have less forward bite than pink or magenta and usually chunk and wear out much easier/faster. I have seem them used and work but only in certain circumstances.

Hope that helps a little.