for Hope Tech XC rim – so 19.5m internal.  I have 25mm Tesa tape already – will it fit or should I buy the 19mm stuff ?

Cheers

I would say stick a bit on and see. You usually want the tape to go up the sides a bit and if the rim bed is concave too that adds on another bit.  Normally I would say about 23mm for a 19mm rim so you may find 25mm is fine. Others may say differently

I go with the external width of the rim. As above, once you pull the tape down into the bed it ends up being the right width.

cheers for that, the Hope rim has an external width of 24mm, so will try the 25

wheels have landed 🙂

Also bought some Stans 21mm tape, so will have a try with both the 21 Stans and the 25 Tesa tapes and see how they fit…

I’ve got 25mm tape in my WTB 19mm rims. Just get it in nice and tight and press it down with an innertube.