I have a question regarding frictional force, and how it is related to a contact area. Last week our professor mentioned that the frictional force between an object and a surface is independant of the surface area in contact. If this is true, then why do vehicles in motorsports want to have wide tires to keep as much rubber on the ground as possible? According to the prof's statement, it shouldn't matter. Can anyone explain the prof's statement? Or prove it wrong? Or introduce something that perhaps he left out? Thanks.