Most 16" factory Opel / VX alloy wheels are approx. 10kg, 17" approx. 10.75kg.
Exceptions.....
Vectra-B supertouring 16" are 8.4Kg
Astra 888 coupe OZ racing 17" are 8.0Kg
Both these are 5X110 PCD.
Aftermarket: 16" Team Dynamics Pro Race 1.2 are a good price / weight ratio, these are 7.4Kg
..or factory steel wheels are approx. 8Kg.