Bradley, Looks very nice. I think your paint work is smooth and I like the shade you used. Your conservative use of decals works nicely (Give it the look of a long-range, fleet truck).
As JT said, it can be a real trick to get the tires to seat properly on the rims, looks like you got yours together quite well.
I've built 8-10 of this particular kit. The level of detail versus the lower price tag makes these kits prime for experimentation with customizing (they're quite east to convert to anything from a single axle, day-cab to a stretched-frame/big sleeper rig). With a bit of practice, you might be able to build one of these into that wrecker you mentioned.
For detail work, I've found "Sharpie" markers to be quite useful. Black and silver are great for trim/moldings (as well as touch-up on other painted parts). Red, amber, orange etc are excellent for chrome parts into colored lenses (turn signals, marker lights etc). Finally, to mirror the comment by Ben, keep at it, each build will teach you something new that will help you improve on the next one.
Keep at it and welcome to the Truckin' side!
brinx