Back in the 70s and 80s, its definition was COMPLETELY different: an ugly girl. (a dog, which chases cars).
Whenever the definition changed to a car freak is beyond me. Looks like a media/cultural-generated propagation of the high maintenance gal. (better than its previous definition, then, perhaps?)

Internet persona(s) who happens to follow you and you happen to follow them back and maintain communication with and have a mutual liking for eachother whether it be friendship wise, etc. (Mutuals if more than one mutual)

A girl who is really only interested in a guy because he has a nice car, and it gets him attention, so she wants in on that attention and uses her ass as a free ticket to the car.

If played right by the guy with the ride, he gets to rail a girl outside of his reach because he does have a nice car (or truck... something shiney, tasteful and/or loud)

"Use me for the ride, I'll use you for the hide"
-Sir Mix-A-Lot

A chick who goes out with a guy ONLY for the benefit of his nice vehicle; usually a nice shiny jacked-up 4X4 truck with oversized tires, or even a hot sports car. Hence the name, "tire-biter."

Conversely, it CAN refer to a guy who goes with a girl solely for HER nice wheels.

A tirebiter is a girl who hangs around car meets, car clubs, or car places in general because she likes to fuck around with boys with nice/fast/show cars. Normally they bounce from car to car, either screwing people in the same club or in the same circle of friends. We call them tire biters as opposed to Pillow Biters because they end up biting tires, not pillows.

kustom kulture girls who only date men with cool custom cars

This is the basic definition that somebody is a "dog". A person who looks for sex.