| I run a 180/55 Supercorsa on mine, much better than the 190 standard section tyre.
When the 190 is fitted to a 5.5 rim the bead is forced inwards and this curls the extremity of the tyre away from the intended contact patch with the road and distorts the true section. So the further you lean the further you need to lean to meet the edge of the tyre.
Because the profile is distorted the stability of the tyre is affected and will not behave in the manner the manufacturer intended (especially) when cornering.
I doubt that the majority of us could tell the difference but all I can say is that this is how the issue has been explained to me and I am much happier with the bike running the 180/55 rear on a 5.5 rim
Mind you, the Supercorsa has a lighter carcass................. |