+4 on I-Beams, I prefer Med compound, they hook up awesome where I run (Hobby Hut, Philly, PA - hard red clay) and they last very well too. The Soft's are great but they only last a few hours and burning up AKA's is not cheap. City Blocks up front and I-Beams in the rear works well for me.

I was running on a track that was loose loam/soil the other day and the City Beams worked awesome there too! Huge fan right here!