The conclusion to the adventure of Gollom's tires!

[WiseSage]

Many thanks to everyone who assisted me with my current predicament about wheels of varying sizes. A solution has been found in this matter as a result of the efforts of a skilled dealer. The gentleman working at Mercland, Jay, is a true gem. Who else do you know who would assist me over the course of the next three years after I acquired the automobile from him? Jay came upon a pair of 17-inch AMG wheels that had just been powder coated and included very decent tyres. He offered to sell them to me at a very attractive price, as seen in the picture below. I was concerned that the arches would seem less full with the decrease of one inch, but that was not the case at all.
Also, a huge thank you to Mick at F&M powder coating in Preston, who put up with all of the difficulty and effectively lost money as a result of the situation. I strongly recommend that you get in touch with them if you are located anywhere around Preston and need work to be done on your wheels.
One more question: given that the wheels are now 17 inches rather than 18 inches, how do I determine the appropriate pressure for the tyres? This forum is fantastic!

[TechWhiz]

The recommended tire pressure for 18s should be maintained during the ride. In general, I simply keep everything at 35 PSI across the board; you won't be too far off at that pressure.

[dave783]

According to the flap that covers the gasoline filler on my vehicle, the recommended tire pressure for typical load usage on 17-inch wheels is 30 in front and 32 in the rear.

[PixelMaster]

It's shaping up well!
Due to the fact that the Sport model has a lower ride height than the other trim levels, you may get away with using smaller wheels. It ought should ride a little bit smoother now as well. My opinion has always been that Mercedes-Benz "over-egged the pudding" a little bit by equipping these vehicles with staggered 18-inch wheels and rubber band profile tires.
And Jay deserves praise for going above and above the call of duty.

[DreamWeaver]

Those six spokes have always struck me as one of the most elegant designs there is. A positive result.

[VWDaveBMW]

The end product looks fantastic, and Jay should be commended for his hard work. Keep the placarded pressures that are located within the filler flap, as was previously specified.

Changing the diameter of the wheel by itself will not affect how well the arches are filled (or if they are filled at all), since the total diameter of the wheel and tyre will remain the same. If it didn't, the speedometer would be inaccurate. Visually speaking, there is a little distinction between having more wheels and having less tires, although this distinction is negligible given that the difference is just 1 inch. Even if they are the same size, wheels with different styles (and colors) might seem rather different from one another.