What are the widest tyres that will fit on the rear of a bay window kombi with out rubbing issues?

running stock 5.5 14's at stock height.....

thanks

We have 205/50/16 on the back

Low light or later bay makes a difference with the shape of the rear guard lip.
I would have thought you could fit 205/65/14 easy.
I have 225/60R15 out the back on 8" rims but it is custom offset.