----

 

With or without skis?

I can tell you they add a bit of wind noise when empty. Add the ski rack to them and they add a LOT of wind noise, whistling, howling, thrumming...

 

Enough!!!



Agree, wind noise. As long as you don't pull a Clark Griswall and put Grandma on the roof, you'll be fine.

 

They add lift not downfprce.

 

+1, not to mention the wind noise

 

I think they mostly ad drag.

 

Holy Cow! Now that is impressive! I am going to show my wife this picture when she says there is no utility to my 911!

To the OP -- Also raises your Center of Gravity!

 

What, the Jeep store was closed the day you went shopping for a new car ?

 

The downforce of the roof racks can be determined by the following equation:

[weight of roof rack] + [weight of roof rack contents]

 

Zero.

unless u meant 'gravity' instead of 'downforce'..

roof-rack will only create 'drag'.. and possibly 'lift' at high speed

 

And your overhead clearance.

 

Yes and that's the "extended" Yakima cage with two huge all-weather cargo bags.

I can easily haul 11 carry-on size equivalents between the frunk, roof, rear shelf with plenty of room for little bags + with room for a passenger (+ 2 bikes and tires).

So between the two bags you could easily put 2 Grandmas on the roof though they need to be rather light so not to overload the weight limit. Plus I'd suggest the fetal position vs. sitting upright to help with aerodynamics. I think then they would contribute "downforce".

 

None, though they add a good bit of drag and probably work well as a spoiler as a result as well.

 

Aerodynamically, there will be drag and potentially lateral force from cross winds. Vertically, there could be lift or drag, depending on the specifics of the configuration. If you have things mounted on the racks, I suggest avoiding high speeds.