[Skyco]

Crusher Run is good if you want it to pack down well. No dirt in any I've seen...it is (should be) made from rock that is crushed into all sizes including the fines, which are rock not dirt. It is also called ABC around here- Aggregate Base Coarse. Depending on the quarry it may be available in several different maximum rock sizes. The important part is it is composed of variable sized rock from the maximum all the way down to the fines also known as manufactured sand. This lets it pack well and interlock.
It will however be dusty in dry weather. If you use crushed stone be sure it is mixed size...if all the "rocks" are the same size it will stay loose and if put too deep it will be tough to drive through. I had a site once where they dumped all one size (3/4"?) crushed rock about 6-8" deep, you'd get stuck on level ground in that stuff!