Tire setup

We can never get enough traction related toover a long period of time depends on how the
forward bite in our race cars. The traction controltire holds up to heat and wear. A tire that is a
in this case is making the tires stick while we arelittle harder may sometimes hold up better and be
under power off the turns and down thefaster towards the end of the race when the
straightaway. There has been a lot of talk overtires have built up a lot of heat and are well worn
the past few years about illegal traction controlafter a number of laps.
being used in circle track racing. We know it is4. Angle of Attack--The amount of traction
being used and may have won some races, butavailable from a tire can actually be enhanced
there may be better ways to legally go aboutsimply by increasing its angle of attack relative to
developing more traction under power. Many legalthe direction of the car, but only up to a point.
teams have been able to run faster than theFrom straight ahead, we can turn the wheel and,
ones using illegal means to help keep their tireswith each degree of angle of deviation from the
from spinning.direction of travel, the traction in the tire
Traction-enhancing technology has grown. Weincreases. There is a point we reach where the
have collectively learned about what the tiresgain is reduced and we approach the limit of
want and somewhat how to give those tires theattack angle that the tire can handle. Once that
opportunity to maintain grip with the racingpoint is reached, going beyond causes a sudden
surface as much as the laws of physics will allow.loss of grip and traction falls off drastically. This
Let's face it. There are limits to everything in thisprinciple is true of all four tires whether front or
physical world, so we go in search of finding therear. We will provide more on this subject later.
ultimate limit. We try to learn to recognize when5. Equal Loading--An opposing pair of tires (tires on
we get to that limit so we can stop looking lestthe same axle at the same end of the car) will
we go backwards.develop maximum traction when they are equally
The principle of stopping when you're ahead isloaded. That is a generally true statement, but
true in developing a good handling package. Itupon more careful examination of how we do
remains true when developing the best tractionthings in circle track racing, there is a unique
package. The word "package" is an important one,situation where that is not exactly true.
because we might be using several differentThe situation is when we have a tire on one side
approaches at the same time to enhance traction.of the car (usually the left side) that is built with a
They rarely interfere with each other and eachsofter compound than the opposing tire whereby
one adds a little to the package. Collectively, theyit may be able to develop more grip under the
can add up to a marked improvement in availablesame loading as the opposing tire. So, increasing
traction while under power.the vertical load on the inside tire with the goal of
In this series, we will take a look at the variousattaining equal loading for both tires, by whatever
areas of influence that affect available tractionmeans, may not actually generate more traction
and how we can maximize how our car reacts tobecause of the difference in grip per pound of
those influences. Some are almost the same forvertical loading created by differences in
dirt or asphalt, and some of what we discuss iscompounds.
very different and will be talked about separately.Race Track Configuration
TiresThe shape of the track for both dirt and asphalt
Tires are the ultimate connection between the carcan influence the available traction in several
and the racing surface. That basic principle is not adifferent ways. As we apply power, we need to
new one, but a concept that has always been atknow a little about how the track is banked, how
the forefront when trying to understand ways tothe banking angle is changing coming off the
increase handling performance in a race car. It iscorners, and how the radius of the turn might be
again at the very top of the list when we discusschanging. A highly-banked racetrack is very
traction under power.forgiving when it comes to needing bite off the
There are five elements that influence thecorners. There is so much downforce due to the
amount of traction that a set of dirt or asphaltbanking and associated lateral forces, that many
tires, the rears in this case, will develop:times the tires are loaded to the extent that the
1. Vertical Loading--Increasing the amount ofavailable amount of horsepower cannot break the
vertical loading (weight) on a tire increases thetires loose under normal conditions with a balanced
available traction, but in a nonlinear way. As wesetup. The tracks we often worry about getting
increase loading on a tire, it will gain traction, butoff the corners are the ones that are flatter and
not in exact multiples. If a tire has "X" amount ofwith less surface grip.
traction with 400 pounds on it, the traction will bePitch Angle
less than double as we apply 800 pounds ofThe severity of change in banking angle of the
loading to it. The amount of traction will be lessracing surface in the portion of the track where
than 2 times X.we are initially accelerating can cause changes to
2. Contact Patch--The size and cross-sectionalthe pitch angle of the chassis that works to
loading of the contact patch helps determine howunload one or more tires, reducing traction. A
much traction we will have for a particular tire. Antrack that goes from high banking to low banking
added area related to the contact patch andfairly quickly can cause the left rear tire to unload
traction involves grooving and siping dirt tires andquickly, making the car loose.
will be discussed later on.There are two ways this can happen. One is
Reducing the air pressure will usually increase thewhen the outside edge of the track drops in
size of the tire contact patch. That would seemelevation and the right front tire follows the
to enhance traction, but excessively low or highdrop-off. This lifts weight off the left rear tire,
pressures may reduce the loading on portions ofcausing loss of traction in that tire.
the tire so that the total loading of the tire isThe other problem occurs when the inside edge
reduced and we end up with less available tractionof the track rises up to match the elevation of
for that tire. There is an optimum operating airthe outside edge of the track. As the left front
pressure for each tire that will offer maximumtire rises up, the left front and right rear pair of
contact patch area and equal loading across thetires become more loaded, momentarily causing
width of the patch.loss of loading in the opposing pair of tires. The
Camber also affects the size and cross-sectionalloss of crossweight percent (right front to left
loading of the contact patch. The correct camberrear) makes the car lose traction in the rear.
angle compensates for the deflection of the tireA track that has a decreasing radius in the latter
sidewalls as the lateral force is applied when weportion of one of the turns can cause a car to
turn the car. More or less camber than idealdevelop a loose condition at that point. Usually,
means one side of the tire will support moreolder tracks that were originally dirt and then
weight than the other, which also reduces traction.paved retain a straight front stretch and a
3. Chemical Makeup--The chemical makeup of therounded out back "straightaway". This "D" shape
compound of the rubber will help to determinecauses Turns 1 and 4 to be a smaller radius than
how much traction is available from a tire. ATurns 2 and 3 for that reason. So, it is difficult to
softer tire will provide more traction, but theaccelerate from Turn 4 because of the
maximum amount of traction that can be utilizeddecreasing radius.