Personal observation on the wheel issue:
The wheels were the issue that surprisingly gave me most pause with my Model X Signature order. I usually abhor too large wheels and too wide tires, usually being happiest in the 225-245/17-19" compromise depending on the car, even with cars that would otherwise scream for larger wheels given their equipment level...
My Model S P85 has the 19" wheels and I have been happy with them. Just cleaned them up this weekend and after two years no curb rash, which is great. Same would not have been true for larger wheels even though I try to be careful.
The reason this, usually a no brainer, gave me pause with the Model X is two-fold: First, the Model X is a large car and the 20" option does seem a tad small on it externally. Second, with the Signature order, the 22" wheels were included in the price - an expensive item to leave out without compensation.
I think what was the decider was the reported 15% range drop on the 22" wheels. I know I'd dislike the drive, be more susceptible to curb rash and be subject to lesser range (and lesser towing range, though that's not a real issue for me). Also, I wasn't a fan of the 22" design and found a more preferable design in the 20" selection.
So, I ate the perceived "cost" associated with getting only 20" for the Signature and have been content. It was the right choice for my driving preferences, but externally the 20" are more modest on such a large car. In the end, I guess modesty is my preference in wheels.
