Moto Guzzi used to use rims similar to BMW's. If you search a user group you should be able to find out the sizes and details (maybe even some good rims). Any good wheel shop may also be able to answer those questions. I would find this of interest if you get any positive answers.
Here's a better article on the wheel works job:
http://www.streetchopperweb.com/tech..._spoke_wheels/
Another shop & 'wisdom':
http://www.woodyswheelworks.com/wisdom.sht
http://www.woodyswheelworks.com/bmw.shtml
BMW pic:
http://ourworld.compuserve.com/homep...ls/GS-tube.jpg
Check out the Jupiter wheel/rim:
http://www.bankeperformance.com/flattrack/rims.html
