Create a hexagon n-gon and then create a circle inside of it. Attach them so they become one object then add a shell modifier to them to create a nut for the rim. Collapse the stack and then convert it to an Editable Poly.
Chamfer the edges as needed to get a nut that looks like the one in the picture. Now just put a cylinder through the hole for the screw.
Duplicate it 4 times and place them around the rim, lined up with the five holes in the rim. Make sure you roate them randomly so they are not all the same. The picture shows the final product. You can now group all the parts together and duplicate it 3 times for the rest of the tires. You can also make a duplicate for the spare tire.
Now you can put everything together that we have modeled and you should have a nice car ready for texturing. Unfortunately, you will have to figure out the texturing of the car yourself as I don't have the time to add more to the tutorial, much as I'd like to.
I hope this tutorial was of some help to you. Feel free to email me and let me know what you think of it at [email protected].