I have a 61/2 rear rim and it rides better with a 190 but you can check cos it is written in the rim

ok cool, thanks will check that out.

I believe in years gone by some bikes were fitted with 6 inch rims but mine has a 5.5 inch rim so i don't see any reason why a 180 won't go straight on and speed the steering up...........but you would think that the technical bod (Steve Male who has been at Dunlop for years) knows what he's talking about.