I know all of the cool kids are going to disc brakes but here in Florida we don’t even use our brakes. Those new aero gravel wheels look positively awesome for fat, comfy tires but what about with rim brakes? What’s the best bet for 40mm wide tires and rim brakes? And don’t tell me Mavic Open Pros LOL 
Joe
40mm tires will defeat any aero gains from deeper rims so just get the ones that look the best to you. For wide tires, you want the widest rim you can find like 25mm internal.
I wonder if you can even find these kinds of rims for rim brake.
Flo claims a little over 5 watts with their aero gravel rim vs. the open pro with a 37c wtb riddler so wide tires won’t defeat any gains but how much vs. a “modern” rim is certainly open to debate
Ha! Well there may be some merit in doing just that!
Look at HED or Hunt. You don’t need more than 21mm wide - honestly, I’m not sure I’d go over 23mm for a 40c tire (at least, it wouldn’t be optimal).
You don’t want your tires too round but you also don’t want them squared off. WTB has some good info on their site about this.
If 5 watts helps you justify the purchase then so be it. That is 5 watts over the total worst case scenario of an Open Pro with probably 32 spokes. Just going to a modern 24 or 28 spokes probably saves 5 watts.
That makes sense. I guess I’m just dreaming of a supersized Zipp 404 or something
It sure might!