Wing?

A wing can definately help out w/ additional downforce on the truck. You'll lose a little top speed but gain traction on the wheels where your wing is placed.

How much downfoce depends on the surface area of the wing, the grade at which it sets, and your speed.

The grade is extremely important however, if its neutral or has a "positive" lift you'll get the opposite effect, at speed. This would be a bad thing.

Decided to find a linky. This one looks pretty good, and not overly technical -> http://www.mustangsandmore.com/ubb/D...dynamics2.html