Another wheel question

Am looking to fit 55mm spacers with std ES setup (235, 70, 16s) on my 300tdi which would make wheels protrude 290mm in total. From the 'guide to tyre sizes sticky' would I need to make any further mods than with 285 wide tyres:
285/75R16 11.8 33.0 8.9 630 14 M/T Rear fender trimming Front endcap trimming Steering stops Bump stop height. Front fender trimming.

«bump!!»

Okay have measured up and realise that with a 55mm offset the wheels would stick too far out of the body to allow them to fit in the arches under load.
So my next question, what is the widest tyre that will fit on a lr eom (300 tdi ES) rim ? Thanks