you would have to put the lug bolts on with spacers to make sure the rotor is secured as if you had wheels on. the dial indicator would then tell you if it is out of true or not. sometimes an inanimate object such as a pencil point held securely on to the caliper will tell you the story.
1993 300e-2.8 - gone now <sigh>
"Do not adjust your mind, it's reality that's malfunctioning"