Password:JDM says that the wider fenders that feature deeper air-outlets are designed to accommodate a 20×11 wheel shod in 315/30/20 Toyo R888 rubber which are the widest tires available for the rear-axle of the factory model.
If you're interested, the price for the wide front fenders is set at $3899.99.
Source: Password:JDM , Via: Gtrblog