zipp gravel tires are vastly different from normal standard tires on thread width, puncture belt and full bead width. They don't allow just any 40mm tire on their xplr wheels but only their dedicated tires. Using normal 40mm tires on 32mm+ iw wheels is mostly okay in tests (yeah they won't get rip off anyway) but they balloon up too much (meaning the badged spec useless and aero penalties) and the cross section layout would be sub-optimal from the tires' original design which results in RR penalties.
I just checked the Zipp G40 XPLR 40mm. It has the same unmounted tread width like the Michelin Pro 5 at 45mm. Sure the casing width is more (89mm vs. 107mm), due to the 40mm specification. Which looks like more or less average in the 40mm tire cat. I don't see much information on the puncture belt.
From BRR on the G40 Zipp tires:
The weakest point seems to be the puncture resistance of both the tread and sidewalls. The low scores here are probably also partly attributed to the "fishnet" style puncture protection that will only work well on punctures bigger than 3 mm.Regarding the other claims:
True, the specified tire width is different than the actual one on a wide rim. Acc. ETRTO standards the normal inner rim width for a 35mm wide tire would be between 17-20mm.
Aero penalties of wider tires is rather small (less than aero socks delta). Afaik it's 3,6W for each 10mm of tire for a pair of tires at 30kph. But I could not find any data on aero testing for wide tires with wide aero wheels.
Regarding the RR penalty on the wider rims, I quote BRR again:
Peak rolling resistance performance seems to be reached when the rim width is somewhere between 65% and 75% of the specified width of the tire. Our other conclusion is that a rim width that is within 50 to 80% of the specified tire width results in performance that is within 99% of peak performance. Only when the rim is narrower than 50% of the specified width of the tire, performance starts to drop-off at a faster rate. The drop-off is small as you'll still get 95% of peak performance when the rim has a width of only 30% of the specified width of the tire.My tire-inner-rim-width combination is at 82% is a bit out of the optimal range (65..75%), but I lose around max. 1% of performance in that regard. This would result in a penalty of 0.276W (for both tires). Is this worth mentioning? I guess not.
Please let me know if you find valuable information on the topic or correct me if I'm wrong.
But other than that your post doesn't include much information and seems like a opinion rather than a facts.
