Technical Bravo handling on different size rims

[Bravo MBY 1968]

Hi there,

My 1.9 Mjet 150 Dynamic currently rolls on 16s with 205/55/16 rubber.

I'm thinking of upgrading the wheels to either 17s or 18s (in both cases would be Fiat with correct offset etc).

Does anyone have any experience of the difference in handling and ride between the various different sizes?

Suspension is standard, though I do have a front strut brace

Is it an Ultra racing strut brace