I am looking for a wheel about so big:

To be used on the smallest wheel motors.
Anyone know if there is one out there or could perhaps do me a massive favour and make one?
I had a look at editing the .gmf of a wheel file but is it possible to edit wheel size like that?
Also, which is the best free or moderately cheap alternative to 3DS Max? I tried Blender but I don't like it too much.
Thanks for the help.