Im running 235's, but thats on 8x18's ET45 and they seem the right size. I probably would not go wider on the standard 7.5 rims than 225's as its the right match.
A quaife is £575 but thats plus the bolt kit and sundries.
For some reason i thought the standards were 8". Duh.
Think i will be sticking to the standard tyre size having read the explantion about grip/friction above. I will be investing in some spacers though, either 8 or 10mm as the car looks too puny from the rear.