Wow! Some great info and picts here! I've been missing out!
As to the original post, isn't the Cayenne already built as an Expo vehicle? That's how I use mine. In my experience, the only needed expo worthy accessory not included with my truck is the 18" wheels. I have destroyed some perfectly good low profile tires (because this truck was ordered with the 20" techno wheels) on sharp rocks and now its time to get a dedicated off road set.
So,
Has anyone been successful at modifying the body to fit the larger 275/65 18 tires? I understand the 265/65 18 tire rub is minimal enough to not require body mods. And, I have seen at least two rally trucks running the 275/65 18 Cooper STT's with the lower front bumper (including the fog lights) removed. I just purchased a set of the '11 Cayenne S III wheels and one used 275/65 tire to test this setup before pulling the trigger on a complete set. They should be here next week. My goal is to re-work the lower front bumper to keep the original look, but make room for the extra inch of tire diameter. My plan is to remove the front mud flap, cut off about an inch and a half, flex forward the wheel liner, reattach liner and reinstall the mud flap.
Would LOVE to hear from someone who has tried this, even if not successful.
As far as I can tell from all my research, the only spot I need to worry about rubbing is the front lower bumper and liner. However, there is also the upper inside ball joint I worry about. My 275/45 20 tire is so wide that it goes under this bolt by about an inch. I'm hoping the narrower taller tire will then rotate beside it. Maybe they use spacers on those rally trucks??