The foot peg rubbers can be replaced.
On a 2 valve K bike, the front and rear peg rubbers (known as "bushings" in the BMW parts catalog) are the same and the part number is 46711454887.
On the K100RS4V or K1100, the front and rear peg rubbers are different. The front ones are the same as the 2 valve ones - part number 46711454887. The rear ones are a bit shorter and their part number is 46712310401.
On a K1, all four foot peg rubbers are part 46712310401.
Installation: Like grip rubbers, the easiest way to install them is to spray the inside of them with hairspray. This acts as a lubricant initially to slide them on and then sets up to hold them in place.
Tip for the thrifty: Since the front edge is what wears you can effectively double their life span by occasionally swapping the left and right sides. (The cheapest part on a BMW is the rider.)
