Originally Posted by MacCool

Physics is physics. These friction concepts have been known since the time of Coulomb (18th century). You can prove the concept mathematically yourself using the formula I included above. Ffind the variable that represents contact area. (you can't....it doesn't exist)

Contact area has nothing to do with friction, and increasing contact area won't increase your traction. Now, if you're going to track the car, then you'll want wider tires for the same reason race cars use wider tires...to keep them from getting greasy when you really push them on the track. I'd be pretty surprised if more than a few people here on this forum had the skill to push their Z, even an FI Z, that hard on the track where the difference between 325's and 275's would affect your ability to run the car.