The road diffuse mix map would probably take up one whole tutorial by itself, so here's the road's material navigator (only the diffuse slot), to keep it short.
For the grass mat, first I added an uvw planar map, and then in the material editor I applied a perpendicular/ parallel falloff map in the diffuse slot of the grass material (so the grass would have different shades of color depending its angle to the camera). The first map slot I added a mix map. In the mix map the first color I change to a dark yellow color and for the second slot I added a bitmap image of GRASS2.jpg. Then I added a gradient ramp map in the mix amount slot to simulate the transition from the green grass bitmap to the yellowish color.
For the plane grass objects I got the texture by pre-rendering the model of the tall grass in different side angles using the same lighting setup, and saved it as a TGA image file with separated alpha channel. Then I added the tga color image for the diffuse slot and added the alpha map image for the opacity slot of the plane grass material.
For the tire texture I wanted to get a clean tread grooves and a dirty groove. I needed to make a bitmap image which I could use as a mask map. The first thing I did was to turn off the bend modifier on the tire object and placed a new plane object underneath the treads, revealing only the extruded part. I gave the plane a matte shadow material so it would show only the black background and gave the tire a 100% self illuminated white material. Then I rendered it from the top view, making a blk & white map which could be used as a mask map later on