For myself, I create the wheel blur models by taking a side screenshot of the wheel, then using a radial blur in GIMP. First a low level blur, then a pretty much complete blur. This just maps to a lower detail model (flat at the visual level of the spokes, I guess). I've been thinking about how to improve it visually but haven't managed to come up with anything decent yet.
I've opened up a whel in Z Modeler, and dragged some faces around, but it's sadly above my capablility to do this. I've had a look at some other wheels, from a Ford Scorpio, which have blur effects. I can't take a wheel and make it like that.
Hmm... in ZModeler the easiest way to model it is probably:
Create a spline (line-strip). Draw it along the profile of the wheel (about the level of the face of the spokes), then out around the tire.
Looks basically something like this, a cut-out view.
Create>Surface>Revolution. Go to a "front" view of the wheel (side view, left or right). Click the spline, click the center where you want it to be. Enter number to revolve (probably 32 or so is good). If it asks you to cap, that just means it fills in faces at the front and back which depends how close to the centre the spline goes whether you'd want it.
I have 1.06f and I have to restart it after every time I use the revolution tool. Not sure if other versions work better. Splines also make it crash sometimes so I usually delete them.