Was reading this article about the GD spoon Fit and it talked about why they don't use wider tires:
Honda Fit by Spoon - Tuner Car - Honda Tuning Magazine
"On the other side of the brakes are 15-inch Spoon rims wrapped with 195/50 Yokohama ADVAN tires. Why so small? "We didn't do major modifications to the car, so 195 tires were plenty," Sensier says. "If you add more tire, that adds more load, which stresses the suspension more. I didn't want any of that.""