That's very interesting Renato.Although I won't need to change my tyres until much later this year,whilst waiting for my garden to dry out,I've been doing some research on tyres.
From what I've read here and more generally,the Continental 7 appears pick of the bunch at the moment.The choice,as you've noticed,is limited because of the staggered sizes on the RC.
I'm trying to get away from Bridgestone,as the last 4 cars of mine have all had them and I find them quite noisy and on one car,they suffered from cracking.The noise aspect is more noticeable,as the RC is a relatively quiet car,so tyre noise becomes more intrusive.