I've been running rubber on my OB4, its around (camber gauge) -.5/f, -1/r. With pretty even wear thru many sets of tires. My Racer 2 has Prolines Purp, double Purp combo, softer in the rear, 24mm/f, 28mm rear, camber @ -1/f, -2/r If I recall correctly.
Off topic: when I put the f/oneway in the Ob4 I had more roll ! ! LOL. :wink: