Tyre fitment options for 17x8.5" Turbines/Throwing Stars on e34

[genphreak]

Hi all,

Last time I bought new tyres for M5 rims, I got 'standard' 235/45x17 Michelin Pilots. Great tyres but my pet hate is the rims stick out enough to be easily damaged if I lend the car to mumma to go shopping. On a 17x8 ET20 rim, can I fit a slightly wider tyre to avoid the problem?

Stock tyres are 235/45x17. Theoretically these have a 106mm wall, Est. diameter 643.3mm

The options seem to be:

1. 10mm wider; lower 245/40x17 98mm wall, Est. diameter -15.5mm; 627.8mm
2. 10mm wider; 245/45x17 higher 110.25mm wall, Est. diameter +9.1mm; 652.3mm
   The additional sidewall (for shock absorption) and width (for rim protection) would be beneficial for the car. I think it will handle the extra width just fine, but will the additional 9mm diameter cause problems apart from a low speedo reading?
   
3. 20mm wider; 255/40x17 higher 102mm wall, Est. diameter -7.5mm; 635.8mm
   Will they rub? Where?

Not a good set of options really, maybe I have to buy stock and just never let anyone else park it...

Any experience/comments are welcome. Hopefully someone will have some good news for me ;-)