Re: (john S.)
The DA's office might not get involved in the issue between the guys who own the business, but it might get involved in your issue. The difference is that, if the guy who took the stuff really is a "partner" in a "partnership" (as opposed to a "member" in a Limited Liability Company or a "shareholder" in a corporation), he may, under the law controlling the partnership agreement (or Colorado law if no formal partnership exists), have as much right to possess the assets of the partnership as any other partner and therefor may not have violated any criminal law with respect to his other partners. In your case, however, you have given money to the "partnership" and "it" owes you a set of tires. Depending on Colorado law (I'm not familiar with it), the fact that the partnership took your money but didn't send you anything in return may constitute a criminal offense. It almost assuredly constitutes a civil offense - but the cost of suing would probably greatly outweigh any recovery you might get.
Having said all that, you might try contacting the Colorado Attorney General's consumer protection office. State consumer protection people are great and, best of all, FREE!! It's altogether possible that the warring factions will come together long enough to send you your tires just to get the AG's office off of their back.
Best of luck.