Depending on whether you'll be driving on a twisty road-racing circuit or Decker Canyon, a set of sticky tires can be worth 50, 100, or even more horsepower. Slippery tires won't allow a car to translate its power advantage into cornering force and acceleration.

Here's a real-world example: Several years ago when I was organizing an event to give Michelin employees some seriously fast rides around a test track, I fit a 2001 Mustang GT with tires intended for a Dodge Viper and made the Ford nearly 3 seconds a lap faster around a 1.1-mile road course than a 1999 Porsche 911 shod with new, original-equipment tires.

The 911 enjoyed an advantage of roughly 40 hp. Its suspension was far more sophisticated than the Mustang's—a car that could trace its lineage directly to the 1978 Ford Fairmont. Both vehicles were stock except for roll cages and six-point racing seat belts, and the drivers were each professional tire testers and race drivers. (The Porsche driver, a Frenchman, was usually a bit quicker than me in the Porsche, and I was always better than he in the Mustang.) Yet your humble narrator beat him around the track.