Just for grins, what size are the slicks/wheels. I had a car that would move around from too narrow of a wheel in the slicks with too little air.
I experienced that same issue using 28 x 10 slicks on 8-inch rims. I couldn't get a decent footprint unless the air pressure was so low the back end would start to sway back and forth right about the time I'd shift into high gear.
