Originally Posted by
HTupolev
Why? In my experience, one nearly always wants rim tape under the tire's bead. Most rims are dimensioned for it, and can suffer from sloppy tire fitment otherwise..
Tape that extends to both walls of the rim...especially thick tape like Velox...increases the effective bead seat diameter of the rims and most rims I own definitely don't need more in this area -- the tires seat pretty "firmly" on their own! My experience is apparently not universal, but I specifically avoid the bead seat area when fitting rim tape. Not directly related to the original question, but I've gone to using the very thin mylar type adhesive tapes and I do two wraps, covering the spoke holes (of double wall rims) only. I do use Velox with single wall rims, where the spoke nipple ends must be contended with and where the rim has a clear channel for the tape, avoiding walking up the side.
I will say that I'm sure the very thin mylar/tubeless type rim tapes don't increase the bead seat diameter appreciably...my practice of avoiding the bead seat area comes from when I used to use Velox on everything.