If its a track purpose ask your self these questions .

What are my grip and traction limitations at the moment .
What handing balance and characteristics does the car have at the moment .

Is the bigger footprint going to have a positive or negative affect on your driving style . Its really a personal question from your point of driving as in what do you want from the experience .

For instance the size rubber I run I like because the car moves around alot but is very controllable and it puts a smile on my face, because the fun factor is there for me . But #1 for me is enjoyment not being ultra competitive. If I went wider my times would improve but It would lose the fun factor for me so I say no. Even though wide rubber looks frikkin awesome .