The issue isn't about oscillating car wheels, nor wheels at all for that matter. The scientists performed their experiments with a flat, inclined un-suspended plow blade; when it got above a certain speed the plow blade created ripples just like a wheel does.
The bad news is that it will be long time before the phenomenon can be stopped: "Just about any time a malleable surface is acted upon by a sideways force, you will get ripples." Since it doesn't look like ripples are going away, scientists could turn their attention to suspension systems that will "eliminate the bumpy ride." Hat tip to Michael S
[Source: Science Daily]