Employment Law Questions? Ask an Employment Lawyer.
While truck drivers have notoriously been disinfranchised as "independent contractors" - and therefore unable to claim compensation for many things such as overtime, wage and hour claims, and other compensation - there has been many recent developments in case law (particularly on the federal level) that is starting to change this.
Your best option is to speak to a local employment law attorney (not a worker's compensation attorney - these are two different types of law), and ask for a consultation - most of these attorneys will provide you with a free or reduced cost consultation (many will at a minimum provide you with an over the phone consultation if not meet with you in their office).
They can go over your employment contract, the actual work that you do, and see whether or not you are being properly categorized as an "independent contractor" or if you should be categorized as an "employee" in which case you can force your employer to compensate you more fully (and may even be entitled to additional damages for wrongful withholding of wages).
You can find local attorneys using the State and local Bar Association directories, or private directories such as www.AVVO.com; www.FindLaw.com; or www.Martindale.com (I personally find www.AVVO.com to be the most user friendly).