two wheels - one wheel spindle-- axle taper bearings- roller bearings innertube -- tubeless spoke wheel-- aluminum wheel I guess it is down to the tire only . My theory , and I am sure someone will be able to explain it better than me, is gyroscoptic inertia ( hows that for a fifty cent word) I found a good explanation on wikipedia under gyroscope. The rotation changes dirrection and causes the wobble as the inertia is in a different dirrection.Trying to hold or pull in a different dirrection causes it to get worse. The only cure is to stop or slow the spinning to stop the inertia. On my car, thru the winter, the only thing I will do beyond normal maintainence is to add balance beads to see if this will make a change. I did not solve the problem, but maybe someone smarter will be steered in the right dirrection.
da prez
I know a couple of guys here in Arizona who have cured the problem by messing with the caster and set the camber to 0 by bending the straight axle. They also have a bit of a toe in. In addition to that they have a sizable tie rod. How much flex does you chassis have. It might be bowing the straight axle as you accelerate. You might want to check out the setup on a front engined dragster.