| The tire you use is one of the most important | | | | your engine produces substantial power, you should try |
| suspension tuning choices you will make in building and | | | | to maximize the width of the drive wheels to make |
| racing your car. Even a car with a professionally-tuned | | | | sure you can get the power to the ground. |
| suspension will not be able to clock fast laps or handle | | | | The third factor to consider when choosing a tire is |
| well on a poor quality or inappropriate set of tires. The | | | | sidewall height. A tall sidewall flexes more than a |
| major performance factors to consider when choosing | | | | shorter one. Therefore, a short sidewall tire will provide |
| tires are compound, contact patch, and sidewall height. | | | | a more precise steering feel than a tire with a tall |
| A softer compound tire will have more grip but will | | | | sidewall, but using a taller sidewall makes the car feel |
| wear out quickly while a harder compound tire will | | | | more forgiving and less twitchy. Also, a short sidewall |
| have less grip but will last for a relatively long time. | | | | tire makes the ride harsh on the street. For a |
| Your choice of compound is mainly affected by the | | | | dedicated race car, this is obviously insignificant. |
| type of racing you plan to do and your budget. For | | | | Tire pressure can be adjusted to change the handling |
| serious racing, you will need a soft compound tire to | | | | characteristics of your car. By increasing tire pressure, |
| be competitive. If you plan to do mostly street driving | | | | you cause the tire profile to become more round, |
| and/or do not have the money to frequently replace | | | | which decreases the size of the contact patch. You |
| tires, go with a harder compound. | | | | also cause the spring rate at that corner of the car to |
| The second factor to consider is tire contact patch, or | | | | increase since you are making the tire harder and, |
| the area where the tire makes contact with the | | | | therefore, "bouncier" by filling it with more air. Both of |
| ground. You want the biggest contact patch that you | | | | these results take away grip from the tire. If you |
| can get. When more of the tire is in contact with the | | | | increase front tire pressure, the car will become tighter |
| ground, the tire can exert more force and allow your | | | | (added understeer), and if you increase rear tire |
| car to achieve higher cornering speeds. | | | | pressure, the car will be looser (added oversteer). |
| The contact patch is determined by the width of the | | | | Lowering tire pressure causes the tire to sag, which |
| tire and the tread pattern that is on the tire. (Usually the | | | | increases the size of the contact patch. In addition, it |
| width provided in the tire specifications is the overall | | | | decreases the effective spring rate at that corner of |
| width, or section width, of the tire, not the width of the | | | | the car and makes the tire rise in temperature. The |
| actual part of the tire that touches the ground. | | | | additional rolling drag (or friction) produced by the |
| However, some manufacturers will provide the actual | | | | sagging of the tire is responsible for the temperature |
| width of the contact patch, which should be slightly | | | | change. These factors provide the tire with more grip. |
| smaller than the overall width of the tire.) If the tire has | | | | If you decrease pressure in the front tires, the car |
| very little tread, the contact patch will be larger (since | | | | becomes looser, and if you decrease pressure in the |
| there are fewer gaps on the tire surface for the | | | | rear tires, the car becomes tighter. The temperature |
| tread), and the tire will have more grip. A tire with no | | | | increase may be desired if it will allow the tire to heat |
| tread, used only for racing, is called a slick. Slicks will | | | | up to recommended operating temperature. However, |
| maximize your car's cornering ability but are illegal and | | | | overheating the tire can lead to loss of grip, "chunking" |
| dangerous on the street. As a rule of thumb, if you | | | | (large pieces of rubber tearing off the tire), and |
| plan to drive on the street, use a tire with at least three | | | | generally faster tire wear. Before making any tire |
| vertical treads. These are often referred to as | | | | pressure adjustments, find out the recommended |
| semi-slick tires. | | | | minimum and maximum pressures for your tire from |
| You can use your choice of tire width to change the | | | | the manufacturer. Also, experiment with tire pressures |
| handling characteristics of your car. For instance, if | | | | by changing them in small increments until you find the |
| your car tends to understeer, you can increase the | | | | ideal setup. |
| width of the front tires to improve front grip. Also, if | | | | |