Thought this was pretty interesting. I asked my dealer why they put tyres with rim protectors on when they dont work when parallel parking even if you slightly hit the kerb.
His explanation was pretty simple - its not designed to work when the wheel is parallel to the kerb. He said it was to allow people to mount up kerbs with full lock without kerbing the wheel.
He was so confident that he told me to stand outside and mounted a 5 inch kerb with an IS F-Sport on full lock - guess what!? No kerbing on both front and rear wheels! He dropped the car off the kerb using full lock and still, nothing!
He did the same with another IS which had just been traded in and needed a wheel refurb (had a slight scratch on it). This car had 40k miles on it and the owner had traded it in with winter tyres on which didn't have any rim protection whatsoever.
He mounted the same kerb in the same way and the front wheel got kerbed about half way around.
I took a very close look and it appears that when you fall off the kerb with full lock, the protruding lip actually stops the wheel coming into contact with the kerb itself and because its at an angle, its strong enough to ensure the wheel doesn't get damaged. When the wheel is parallel, the protruding lip just gets grinded and isn't very strong as it almost gets squashed which is why it leaves rims with chunks missing from them.
Just thought it was pretty interesting.