What are the rim depths of each wheelset?

Both are 45mm.

The first pair has hook and the manufacturer claim they are faster with 25mm
The second pair is hookless and the manufacturer claim they are faster with 28mm

I'm using 28mm on both, and if there is anything the 1st one look a little wider (1mm)

My guess would be that there is zero difference between them.

It's not just the depth that matters, it's also the profile. The older "V" shaped profiles are less stable in gusts than the more "U" shaped profiles from designs that started with wheels like the firecrests. I have a 50mm V-shaped Mavic Cosmic Carbone that is less stable than a 90mm HED J9+




There are even the "humpback fins" on some designs that proport to help with stability.

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Shouldn't someone ask the OP what "stability" means before offering suggestions?

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"Go yell at an M&M"

What might be happening could be related to what Josh shares here:
https://forum.slowtwitch.com/...ost=7736116#p7736116

A wider tire that makes a rim slightly less aerodynamic can improve crosswind stability, because it makes the front of the rim have less lift/side force at yaw while not substantially lowering side force in the rear.

When total wide force in the front of the wheel is greater than in the rear, the bike feels more “unstable”, because the wind is steering the bike into the wind (due to counter steering), and… well I can’t say exactly why this feels more unstable, but the consensus is that it does.

I’ve noticed this on my Jet 9’s. They are 26mm at brake track with a max width of 28.5mm. With “23mm” tires that measure 25.5mm, you feel crosswinds noticeably more than with “25mm” tires that measure almost 28mm. It’s not a dramatic effect, but it’s absolutely noticeable.

…Though I accept that sometimes we think we think we feel things on our bikes that aren’t real :-)

Anyway if you have wheels optimized for 25mm tire and you run a 28mm then, by this thinking, you’ve hurt the aerodynamics but improved the stability in crosswinds. A wheel optimized for 28mm tires is probably more aero optimized but at the expense of stability.

With all that said, I’m surprised that 45mm deep wheels would create enough instability to tell the difference. But then again with high enough wind that would seem more reasonable.

Good question, by stability i mean that the wheels are predictable at high speed in crosswind

And what behavior are you seeing that is not "predictable"?

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"Go yell at an M&M"