So i was walking up to may car the other day and noticed hideous tabs below my side skirts near the wheels (4 - 1 on each corner) peaked my head under to notice their rubber add ons. almost look like scrap tabs.

Any one have any idea what these are for? they look like scrap points but how they would be benificial i have no idea. Took three screws each to take em off. went ahead and did so. looks so much cleaner now.

 

Took mine off too

 

I thought those were for deflecting wind around the tires for more grip.

 

o no,they are the 4 screws that hold the body to the frame!

 

Yep, while not for grip they do aid in the cars low 0.26 drag coefficient.

 

I'll pay for shipping if you want me to recycle them for you... I am looking for a decent set.

 

That would explain my car flipping at 15mph this morning. na jk.

Viper6 - I would however only the front ones are in good condition. Im just going to hold on to them for resale in the future.

Wind direction makes sense as they are made of a hard rubber (so obv not scrap tabs) but its odd that the fronts are behind the front wheels. that theory would make sense if they were infront of the wheels. i dont exactly need wind diversion going in reverse. unless im paul walker doing 180 reverses.

 

Mine are at leading edge of all wheels... for air diversion to reduce lift/air spoil at speed I believe... maybe even quiets the cabin... not sure. Probably have little effect at legal speeds...

 

It can have a significant effect at legal speeds.

They are placed at the front of the tires to reduce aerodynamic drag. The front of the car is subjected to total pressure. Total pressure is the sum of static pressure (no air movement) plus the velocity head. Total pressure increases with the speed of the car. Aerodynamic drag is a function of the pressure differential between total and static pressure.

The wheels wells will have a lower pressure than the total pressure at the front of the car. The rubber deflectors are to increase the static pressure in the wheel wheels, keeping the pressure differential as low as possible. If air is allowed to flow into the wheel wells it keeps the static pressure lower and increased the pressure differential. If the air flow into (and thru) the wheel wells is kept to a minimum, then the velocity of the air is reduced and hence the static pressure is kept higher. Thus reducing the differential pressure from the front of the car to the wheel wells.

Hope this explanation makes some sense. Understanding the concept of total and static pressure (which is necessary to understand drag) is somewhat difficult and it helps to have a degree in Aerospace Engineering. No disrespect intended.

 

well as someone with multiple degrees in Economics and Business analitics i can assure u i have no clue what u just said. no im just kidding.

It makes sense to have the least amount of pressure esp in the wheel well seeing as this is when all your car meets the road. I wonder if this is decreased due to my car being lower then stock. Im wondering if i should put them back on or if its a feature that makes alot of sense in a test tunnel but doesnt hold much aplication in the real world.

in otherwords.

with a lowered car such as myself. how neccessary are they to have... IE can i keep them off.

 

The wind tunnel is the "real world" regarding aerodynamic drag. It is the only way you can truly determine the true drag. Once that is measured and knowing the frontal area of the object and the air velocity, the Cd is then calculated.

Velocity is very important regarding Cd, as drag goes up by the square of the velocity, meaning the drag will be increased by a factor of 4 when doubling the speed from 30 mph to 60 mph for instance.

Lexus obviously went to a great deal of development to allow the LS430 to have one of the lowest Cd of all commercial cars. The UL even lowers itself at cruise speed by about an inch.

Now, regarding whether or not your lowering of the vehicle is positive or negative regarding drag, I can't really tell you. My guess is that it will not hurt drag and might actually help reduce it. A smooth flow of air beneath the car is key, but other than that I would just what you want to do and be happy with it.

 

are you a laywer sir? haha. i believe u said i can keep them off haha.

 

Would it be easy for one of you that has the tabs to take a picture?
I don't see anything like this on my car, and would like to know if they are missing.

It is an open question whether or not they might improve the car's appearance or aerodynamics :-)
Thanks.