Because I have just read all that and then completely forgotten it I will just come out and ask, will Vectra B phase 2 GSi (6 spoke) rims fit my Carlton.
Yes............and look shit!

Why?
Offset, mainly.
FWD rims just don't cut it on RWD cars dude - OK for razzing about (and drifting, where the rear tack being a tad narrower helps the arse get out!). You can do it, of course, but we'll all point our fingers and ridicule.................no, seriously, the wheels would look lost under Carlton/Senator arches.
Imagine putting summat like Saxo wheels on an Elsie!

Omega B seem to suit FWD wheels better, but still wrong......... IMHO.