Really do believe me when I say thank you for all the help, input and opinions you guys have given me.
I have learnt a lot more about tyre suitability for the RSV, and more importantly an RSV with a 6" rear rim.
As I have a Dunlop on the front I'm going to endeavour for a 190 GP Racer or D211 N-tec. If I can get a 190/55 I'll try that, otherwise a 190/50.
When these wear out I'll try Supercorsa or racetec, 180/55.
I'm sure the poor grip was caused by the 180 being pulled 'square' by the 6" rim, getting too hot and the shoulder wearing. This gave a less graduated contact patch meaning the bike was either upright or sat on the edge- it had no grip to offer as I rolled on the throttle and stood the bike up.
Once I earn some more money I'll put this theory into practice- cheers!