[mwilliamshs]

I too was gonna mention the early Insight fenders. Lots of that style on race cars, both professional and the more serious amateurs like on clubroadster.net

That being said, I think Aerohead is right but for a reason nobody's mentioned. The wheels of an OTR tractor go UNDER the trailer when turning sharply. Skirts can be longer but angled in or shorter but stay straight. The landing gear is "break-even" point for trailer skirts whereas on a car or straight truck you can keep the skirts flush to the outside of the tires, which is a benefit whereas the narrower trailer skirts are a compromise.

Seeing the popularity of having dozens of license plates on an OTR truck back in the 70s might likewise lead posters here to believe if the truckers have lots of plates, we should too because they wouldn't do it if it weren't good...but that was another compromise truckers had to make and to copy it would've been foolish.

Next someone will say "yeah I like those angled trailer skirts so I'm doing that for more mpg and also dupicating the 15 liter engine cuz trucks wouldn't have those if they weren't good for mileage"

I do think the 8 tires at the rear of the truck and the necessarily large open area around them is a big source of dirty air and the fairings being stuck inside that is probably an attempt at getting all that air going in the right direction again but unless your vehicle has 8 such tires at the front, I don't think angling your side skirts is going to benefit you.