Originally Posted by
HTupolev
Second, the Stampede Pass has a nominal width of 32mm, whike the 4.5 AR is optimized for tires of 28-30mm. A too-big tire can prevent the rim from smoothly capturing the airflow off the tire, compromising the purpose of the wheels. Not a huge issue, but one that I'd care about if I was dropping $3000 on a wheelset.
I'd care too, but it's not clear to me that exceeding the width of the rim by 1mm per side will cause the airflow to separate. So long as the airflow remains laminar around the tire, across the junction from the tire to the rim, and then following the gentle curve of the rim around to the back you pretty much got the benefit.
Yeah I'd have my own reservations about the 32mm Compass on these rims, but it would be the bead issue you pointed out rather than the airflow one.
The front rim diameter is 31mm. I'd be surprised if someone suddenly lost the aero benefits of these rims going with the tubeless compatible 35mm Compass tire. That's just 2mm wider than the rim on each side, and if the transition is gentle enough I highly doubt at typical riding speeds you'd see the flow separate coming around that tire. I'm no aerodynamic engineer so I could be wrong.