Get a list of the tire sizes and a range of quantities needed and I'll reach out to my friends in the industry and see if we can put something together. Actually, the goods are only half the battle. The logistics of getting them there at a reasonable cost can be a killer for projects like this.

I might be help here too. My wife and I started a donated goods charity in Mexico a few years back, and have worked out a scheme that brings transport costs down to near zero.