Sources:
“The Friction of Automobile Tires” Jones & Childlers, Contemporary College Physics, 3rd ed., 2001.
“Friction” http://physics.bu.edu/~duffy/py105/Friction.html
“Contact Patch” Tire Rack. http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=10
“Fact or Fiction?” Performance Simulator. http://www.performancesimulations.com/fact-or-fiction-tires-1.htm
“How do 30 pounds of air in your tires hold up 2 tons of car?” How Stuff Works. http://auto.howstuffworks.com/question506.htm/printable
“Traction?” PhysLink. http://www.physlink.com/Education/askexperts/ae200.cfm