After doing some research on the topic, my previous statment (the post right above this one) is incorrect. The greater contact surface of the tire only helps with inequal road conditions, as someone stated before. I still believe that if the road conditions were the same in each place, a wider tire would not help for straight line traction. Now, another reason to put some huge drag slicks on is to be able to handle the car off the launch. Weight distribution is not perfectly equal across a drag car, and again road conditions are different, so one tire may loose more traction than the other tire, causing the car to shoot off toward a wall or something. You've seen it before. The wider tires on those cars help gain control back from something like that.