The first bit of information was posted on an RC51 bulletin board. RC51 wheels may be different from Ducati wheels, but you can get an idea of the weight savings. The second bit was posted on the website of a Ducati 888 and 900SS owner.
Wheel Weights Courtesy of Dan Kyle Racing
The most important weight is around the outer rim, this outer weight determines the gyroscopic effect (turning) and affects the brakes the most. So even though the overall weight may not appear to be a significant savings the performance aspect is still there due to less rotating mass on the outer most part of the rim.
FRONT WHEELS NO DISCS
Blackstone carbon fiber 4.85 lbs
Dymag carbon fiber 5.6 lbs
Dymag mag center carbon rim 7.8lbs
Hi Point forged aluminum 8.2lbs (unofficial weight)
Marchesini cast mag 7.7 lbs
Marchesini forged aluminum 8 lbs
Marchesini forged mag 7 lbs
Marvic Penta II 7.5 lbs
PVM cast mag 9 lbs
PVM forged aluminum 10 lbs
PVM forged mag 7 lbs
PVM Colorline 5 spoke two piece 14 lbs
OZ forged aluminum 7.75 lbs
Stock RC51 10.5 lbs
REAR WHEEL WITH DISC AND CUSH DRIVE
Dymag carbon fiber 13 lbs
Dymag mag center carbon rim 12.8 lbs
Hi Point forged aluminum 16.3 lbs (unofficial weight)
Marchesini cast mag 12.7 lbs
Marchesini forged aluminum 16 lbs
Marchesini forged mag 13 lbs
Marvic Penta II 13.6 lbs
PVM cast mag 14.25 lbs
PVM forged aluminum 17.75 lbs
PVM forged mag 12 lbs
PVM Colorline 5 spoke two piece 6.25" 25.5 lbs
OZ forged aluminum 16.5 lbs
Stock RC51 19 lbs
Here are the ACTUAL weights of the magnesium Marchesinis for the sizes shown. I weighed all this myself. The wheels are compared sans rotors. The rears were weighed with cush drives & sprockets (both alloy) since they both use proprietary stuff there. I also weighed the cush drives separately, in case anyone's interested in that. All bearings are in place...
Stock Brembo 3.5 x 17 front: 11lbs, 3oz.
Marchesini 3.5 x 17 front: 7lbs, 3oz.
4 lb difference.
Stock Brembo 5.5 x 17 rear with cush & sprocket: 18lbs, 13oz.
Marchesini 5.5 x 17 rear with cush & sprocket: 12lbs, 6oz.
6.5 lb difference.
Stock Brembo cush drive with sprocket: 3lbs, 3 oz.
Marchesini cush drive with sprocket: 2lbs, 4oz.
Just under 1 lb difference.