^^^^
18" Team Dynamics are a fraction over 9kg and my OZ Alleggerita's are a fraction over 8kg, so I'd guess they are between 8-9kg.
Whether 8 or 9kg it makes a significant difference to steering feedback. But we shouldn't be telling Mike that or he'll want some!
Just for reference, the GTI 18" Monza's are a fraction over 11kg.
I've weighed them all on a friend's DEFRA certified (annually) digital scales (used for fishing club competitions).