After pulling the front wheel to replace my alternator air tube and buttoning the car back up, I found that I had developed a steering wheel shake from about 60mph.

I checked all tire pressures and indexed the suspect left front wheel to each of the five lug bolts, with no improvement.

Then I removed the corrosion and scale from the surface of the rotor hat to which the wheel mounts, remounted the wheel, and went out for a spin. The shake was gone.

My theory is that the crud on the rotor hat was keeping the wheel from mounting entirely flat, so that instead of a circle I was rolling on an ellipse.

 

tire could be on funny. Out of round, but that is easy to check. more than likely, its out of balance, and that can be fixed easily at the tire store

 

This is why most well-trained techs will make a mark on the wheel and rotor hat, or otherwise find a way to ensure that the wheel goes on the same way it came off. This avoids the problem, usually.

 

In this case, neither the position of the wheel (I tried it all five ways, winding up back where I thought I had started, with the lock nut on the red painted stud opposite the valve stem) nor the tire's shape nor the wheel's balance was the problem.

Something else to check: clean mounting surfaces.

 

BTDT -- sometimes stuff will transfer from the wheel to the hub or vice versa when it's torqed down in a different orientation. Then it will never go on right until it's cleaned. Cleaning the mounting surfaces whenever you have it apart is the surest way to avoid the problem, but it takes less time to just mark them so that's more common. You can really end up chasing your tail if this happens at the hub/rotor interface instead of the wheel/rotor interface... don't ask me how I know.