So this is really interesting (bigger tires + lower speedo = aero mode?)

[FrankNBeans]

I recently put on a set of 35x12.5x20 Nitto Ridge Grapplers on my 2020 Limited (stock wheels) and wanted to see how much the speedometer is out. I downloaded a couple of different GPS-based speedometers for the iPhone and tested them in my Tesla to get a baseline and they're all pretty accurate (within 1kph). So back in the Ram, I set my cruise at 100kph and the GPS speedo bounces between 107 and 108kph which is what I predicted with the larger tires.

Here's the interesting part...even though my truck's speedometer reads 100kph, it switched into Aero mode. Previously it would lower at 108kph (66mph) which is in line with what the truck manual says. So if the speedometer is reading 100kph, there must be some other way the truck still knows it's going 108kph. The only other thing I can think of is that it's using the GPS instead of the speedo for the height adjustment.

What do the rest of you think? Or does someone know for sure?

 

[Raminit]

Very interesting, I’m curious also

 

[Limited Bob]

They may use a pressure traducer built into the actuators that sense the pressure on the bottom of the flap. Then in actuated mode they sense the lighter "Deployed" pressure then retract at that point.

 

[Xhumeka]

They may use a pressure traducer built into the actuators that sense the pressure on the bottom of the flap. Then in actuated mode they sense the lighter "Deployed" pressure then retract at that point.

That makes a lot of sense - would also account for headwinds/tailwinds... ie it should drop into Aero mode at a lower "ground speed" with a strong head-wind.