An eighth of an inch isn't alot.......with the weight off the wheels, you shouldn't be applying ALOT of force to measure that. Just a firm 'hell of the palm'. Don't put your weight into it. There are several components resisting your push, and each has a small amount of allowable slop. Added together, they can move a bit under alot of side load.
Once the weight of the car is resting on the wheels, then you apply alot of force to check it.
3 and 9 will check the balljoints and other stuff laterally. Knowing if it'* 3 and 9 or 12 and 6 (or both) is critical. But remember my 'force applied' advice while doing it. Is one more than the other? How much movement with less force (try to describe the force applied).
It might also help us to know WHY you're checking this. I haven't seen any symptoms or complaints. Be as specific as possible in describing what symptoms you've observed and under what conditions. Accellerating? Deccellerating? At a specific speed or above? Turning? Braking?
What have you done so far? Balance the tires? Rotate the tires? Checked the brakes?
Could be rotors out of balance I've read, but can someone tell me the best and easiest way to check to see if the rotors are in balance? I have tried everything else but that, and it still vibrates at 60-70 mph.