Gorilla tape is what @Howard recommends (he’s my go to guy on tubeless). I’ve always used Stan’s Tape but that’s because I had a big roll of the stuff.
Could be so that tape definitely goes all the way across the rim bed, including the wells for the tyre beads. Having started using narrow tape, I now work on the 'wider the better' assumption.
27 tape on 25 rim should be perfect. Tape a bit wider than the tire always worked better for me, some combinations are pretty hard to make it work with smaller tape
Sorry, tape questions:
What’s the generic name for tubeless tape? I know it’s been posted here before.
Anyone know why using a rim rated at 25mm internal it would be recommended to seal with 27mm tape? Seems like an awkward size. Sorry if stupid.