Fair one, In my non-tech mind I could see that being the case for the rim internal being too narrow (effectively folding the tyre as it deforms) but didn’t think of it as an option for wider rims
These types of questions annoy me. You are fishing for someone to say “it’s fine, go ahead and ignore the recommendations”. You know the risks, but you can quantify them. Nobody can. So why even ask?
it’s finding a rationale between why a 40mm tyre (their own xplr) is rated as ok even though it’s been reported to have had multiple documented punctures, and a mountain bike tyre on mountain bike width rims isn’t.
That’s easy: it’s what Zipp has spent $$$$$ testing and found, by whatever criteria they are using, to pass their testing protocol. It doesn’t mean that unlisted tires won’t work, it is only saying what tires Zipp says does work.
I just ordered a new gravel bike building from the frame up. As cool and will “maybe” be the next best thing, too many unknowns and too many reviews with flat issues (tons of thread on the topic). I have no interest being a guinea pig yet.
I ultimately landed on a set of Reserve 40/44 GR. They are 27 mm internal (wider than the standard zipp 303 FC) and also hooked with a fantastic warranty and reviews. They lack the “name recognition” of some other brands, but ultimately feel like the smartest choice until the XPLR is more proven.
That’s kinda my point, in a round about way. The list isn’t saying about the “only” tyres that are compatible, it’s only saying about currently approved
They also say to stick to ETRTO guidelines. The tire you want to run is off by 1.5mm of internal rim width.
Personally, I don’t think it’s a big deal. It’s still a 56mm tire on a 32mm inner width rim and strangely that fits with what Zipp says (min 40mm, max 60mm).
But you take your own calculated risks and make your own decision.
3T, Nextie and Light Bicycle all make hooked 29-30mm wide aero rims. I have both 3T Discus and a set of LB WG44s, and both have been excellent and drama-free over 1000s of very rough miles. If you want wheels that perform similarly to the Zipps but for less money and with hooked rims, look at LB or Nextie.
There were definitely high-profile reviewers who experienced issues with the Zipp Xplr wheel set / tire combo they were provided. But I don’t know that we know what %%%% of reviewers this actually was.
All I can say is that Zipp approved the tire combinations, not that they should have approved them
I only watched one of those review videos and they got a ton of flats and cuts on the zipp tire, less on the other approved tire, and then normal performance on a non-approved tire they installed.
It didn’t seem to be a rim issue like the rim was cutting the sidewall. It just seemed like a too delicate of a tire getting a lot of flats and sidewall cuts.