At nearly every event, there is endless discussion about tire pressures. Newcomers seem to know it's important, but few understand what to do, when, and why. This article will focus on the practical aspects of adjusting tire pressure to achieve maximum grip and handling balance.
Whether you're using race tires, high performance tires, or regular street tires, the goal of adjusting tire pressures, as with all other adjustable suspension components, is to maximize the contact patch, and thus the handling grip of the car. Generally, adjustable shocks, anti-roll bars, replaceable springs, wheel alignment, and other adjustable suspension features are used to provide the majority of adjustment to the car's handling balance and grip. Tire pressure is typically used as a fine tuning adjustment.
However, the majority of weekend track drivers are using relatively stock cars, and have only their tire pressures to adjust. Whether it's your only tuning method, or the last refining step, you need to understand what is happening to the tire during racing, and what the variables are to be effective in adjusting tire pressure. We're going to present this in the form of two phases in determining the correct tire pressures to race at.
First is the large scale setting of what the tire operates best at. Considering the wide variety of tires and cars used at any weekend hobby event, we can expect a wide range of optimum tire pressures to be used at fully heated racing temperatures. Somewhere within the 30-40 psig range is likely for most cars, but that's still a very broad range. If 40 psig is the max, then 30-40 psig represents a 25% window, and nothing in racing is as vague as a 25% window. So first, you have to determine where in this 10 psig band your tires perform best.
The second phase is the fine tuning realm of within 2 psig of the optimum setting. This small adjustable range can be played with based on track conditions to tweak for the best performance at any given time on the track.
We want to first step you through a practical approach to your first few race day's tire pressure settings, then step you through a system to determine the general range of pressure the car handles best at, then finally through some tips for fine tuning. First, however, there's some basic background stuff to cover.
There's a lot to cover, so this article is broken into several sections as listed to the right.