wrote

Hello,

I'm about to tile the bathroom floor. The only thing is, I'm not sure
how to cut to allow the radiator pipes through. They are 15mm pipes
and I've only ever seen tile drill bits up to 10mm, so I can't use one
of those to cut a hole. Do I need to hire a core drill?

Drill a small hole and use a tile saw (like a hack saw with a round
file-looking blade) to cut larger 20mm hole.
You need to remove the blade and put it through the tile hole and reconnect
to saw to cut IYSWIM.
Results are good if you take your time.

Phil