Advantages: Improved road-holding, turn-in precision, and braking.
Trade-offs: The extra weight can overwhelm shock damping and springs, so loose-surface tracking stability is reduced.
The easiest way to improve handling is to “plus-size” your wheels and tires (a term coined by The Tire Rack). It means proportionally reducing sidewall height, increasing wheel diameter, and increasing width to ensure your wider tires keep the same diameter. Prices start at about $1300 for plus-sizing a Ford Focus.