I have always hated those rubber tank grommets. When lubed up, they work great, but if the bike is actually used, it is really hard to pull the 'studs' away from the rubber. Mine cracked, then one disintegrated, then I took the remaining one and split it to have some cushion on the tank. I remember being on the road and shoving cardboard under the tank to provide some cushion and keep it from rattling.
I was just going to get some new ones from BMW but I happened to be in our local 'Runnings' store looking for other hardware for the bike (stainless bolts for the bag mounts) and saw that they had a rubber grommet tray. They had ones that looked like they would fit the K bike, so I bought two ofthem at 3.29 each. Turns out they are a little long: the bottom lip obscures the groove for the retaining circlip. So I cut that part off. Now the grommets stay on the tank when you pull it but there is still a rubber 'sleeve' going through the hole. When mounted with the circlips, it seems pretty solid and gives a nice cushion.
Here is the bottom of the tank with the grommets installed. Yes, that is a JBWeld fix for THE seam leak under the fuel pump. Has lasted for 11 years. I'll do something more permanent when it starts leaking again.