John, were you driving an ally and black car in the morning?
I was marshalling along the slalom and wanted to speak to the driver to find out what tyres he was using as they were obviously carp.
Having said that, as you have the same carp tyres on all corners they shouldn't affect under/over steer too much - it all about the balance.
As others have said, check your rake, soften the front end and overinflate the rears. You should soon have the back end wagging.