Semi made me jealous of his wheel covers
 

I was in the turn lane waiting to get on I-4 this morning, and happened to notice this guy's wheel covers. Pretty cool!

Make a 1 mile a gallon improvement in an Insight and you're looking at about a 1.3% increase in mpg. Make it in a semi and it's more like a 16% increase!

http://ecomodder.com/forum/attachmen...8&d=1431624743

Masilla Valley trucking uses a lot of those, as well as side skirts and boat tails.
I really like the look of the moon wheel equipped trucks :http://www.protruckeronline.com/file...2.22.34-PM.png

(This fella is missing the back wheels though !)

^ I've seen those a lot here in NC (the aero tails). I believe a company called "Trailer Tail" was on the last one I saw...

i've seen some on the tractors but never the trailer.

You can get Moon discs if you want the most aero covers for 14"-16" steel wheels, but they kill most of your brake cooling, and brake fade is both scary and dangerous.

Brake fade is scary and dangerous yes. However, I've yet to hear one situation where an ecomodder had a problem with full wheel covers...

Your vented discs will still run air through them as they are a centrifugal fan. They just pull air from behind the wheel. They just don't have the assistance of a spoked wheel which also acts as a centrifugal fan to some extent.

The only time I've experienced brake fade on a public road was while bedding new pads in my old Ram. 5200 lb truck, and it took nearly 40 "panic" stops in a row from 45+ mph for the brakes to lose it. If you are truly concerned about brake fade from closing off the face of the wheel, I have to wonder what you're using the car for and how you are driving it.

I had a Camaro, one of nearly 2 dozen I've owned, nearly all of which I've driven, and I was blasting down a favorite canyon early one sunday morning.
It was my first spirited run in this car, but the brakes were good in daily driving.
This one has open-face wheels, and even so, by the bottom of the canyon my brakes were about as good as Fred Flintstone's feet. With the e-brake and manually downshifting ( it was an automatic ) I got stopped safely, before wasting a boring hour watching glowing orange front rotors cool down.
Ever since then, I've been putting together my own big brake kits for far less cost than ordering existing kits.

A lot of trucks in California rock the side skirts/moon disks/trailer tails. I talked to quite a few truckers over the course of me working in security at a truck gate. The gains are actually quite good from reports. One fellow I remember talking to said at 55mph he gained 3mpg increase, from 9mpg to 12mpg. It may not seem like much, but when you do close to 50k miles a year, the savings are enormous!

that is a dramatic increase to me.
if that was me, i would have been in EOC mode all the way down.
i don't think i will have any problems when i finally get mine on.