493 Dodge wagon,4.30,caltracs, QA-1 single adjustable about 70 per cent of full stiffness,8inch converter.Phoenix F-9 30 X 9 bias slicks with tubes. I find that any. Pressure less than 18 lbs tears up the tire. Tried less air with variety of shock settings without success. Also tried Hoosiers DO-7 compound which were too hard and spun similarly to what you described. This was all with tubes. My car leaves pretty good with the 18 lbs Phoenix setup running from 1.39 thru low 1.40's depending on conditions. Just my experiences.Others have said I'm off with that much air but I don't have double adjustable shocks to play with at this time so this seems to work for me.