Hey I'm bringing this back from the dead because I am about to change out my front KDWs for the new radial TA spec "test tires" we have been talking about in the other thread.
My Marauder still has the steering wheel "Jiggle" or side to side sawing action, 40 mph and above. If you let your hands off the wheel it literally will saw side to side slightly. The car continues to track straight but the steering wheel does a little wiggle dance.
I have balanced the tires so many times it's not funny. I have my own Coats spin balancer now and it was recently calibration checked by a calibration service before I bought it. I do self calibration checks on the machine every couple times I use it and it always passes. I balance in "fine" mode which reads out to 0.01 oz instead of rounding off to the nearest 0.25 oz like most shops do.
I have also match mounted the tires to obtain the lowest amount of radial runout possible.
I have checked the wheels with a dial indicator w/ the tires off, on both the inside and outside bead seating areas. This is one of the important measurements that a Hunter road force machine would be doing but I'm doing it manually since I don't have a $15,000 balancer. I am getting less than 0.010" runout, peak to peak, on each edge. This is about 1/4 of the max runout allowable per DOT and 1/2 the runout that is acceptable per the factory service manual.
So we can safely eliminate wheel runout and wheel/tire assembly balance as the cause of my vibration.
The tires do not run out much unloaded but that doesn't mean there isn't a stiffness variation in the sidewalls that shows up when loaded.
My suspension bushings and alignment are all great and I replaced the brake rotors with mill-balanced quality replacements.
If its not the tires than I don't know what could cause such a vibration. The fact that it shows up at such a low speed and that it causes the steering wheel to steer itself side to side seems to indicate one of the 2 front KDW tires has something going on once per revolution.