I use this
tyre paste . The main reason is it's called 'honest johns' and it has a picture of a bloke with his thumbs up, so it must be good! Actually it is very good. I've had it for a year and changed around 8 tyres - hardly used any.
I used to use cheap window cleaner from the supermarket and that seems to do the job also. In fact on a difficult bead, i'll still use window cleaner and spray around the tyre whilst pumping it up to get ti to seat.
Oh and I feel for you with the K60!! I wrecked my first ever rear K60 by exerting too much pressure trying to get the last bit on - ripped the bead. An expensive lesson! but I managed the replacement after being a bit more patient.
Removing it is another pleasant experience!!! I had a puncture on the trail and could not break the bead - tried all sorts of methods (mates sidestand trick). We managed to get it to a truck mechanic who couldn't break the bead on his tyre machine - until his bike mate turned up and did some little trick and off it came. Don't know what the trick was! I won't fit another K60 as I know I'd struggle to remove on the trail. Shame as it's a cracking tyre.