the other method of animating a rotating wheel in studio besides keyframing is to use an expression based on the current frame number but that’s only available to autostudio and studio + advanced animation users. unless you have one of those you’re stuck with keyframing, which will indeed work to product motion blur in the raycaster.
or use maya, which is made for that sort of thing.
when i say “aperture” you are right, i mean “shutter angle” under blur effects in render globals. crank it up for more moblur. for more moblur in a single image just set globals to render one animated frame and crank the by frame number to something higher than 1.
in my tests with v9.7 the raytracer ignores motion blur settings, hence no moblur there.