TRACTION CIRCLE (13 of 13) Intelligent Racing, Minimal Spending: The Definitive Introduction To Racing Concepts


Welcome to 13th and final part of this racing concepts series. Remember: the most dangerous words in the English language are “I already know that.”

OK, pay attention. This is where it all comes together.

I definitively stated in a previous post that it is very important to realize that a tire is capable of producing more grip while experiencing a combination of lateral and longitudinal forces.

This concept will lead to huge gains in driver improvement.

If you can understand that more grip is available under a combination of braking/cornering or accelerating/cornering, you will be able to make serious positive changes to your driving technique.


In the Track Analysis post, we briefly discussed two methods of using traction.

  1. Several decades ago it was believed that a tire created the most amount of traction when it braked at 100%, then turned into a corner at 100%, and then accelerated at 100%.
  2. At some point later, thanks to the revolutionary thinking of Mark Donahue, it was discovered that the old method of driving was actually leaving a huge amount of traction on the table.A racecar is actually able to make more traction during a combination of forces.

In other words: if you mix steering/braking or steering/throttle simultaneously, you go faaaaaaast.

It’s important to keep in mind that when combining forces, each force must be less than the total ability of the tire.

More cornering force equals less available braking force. More braking equals less available cornering, etc.

By looking at the traction circle for a theoretical tire (Figure 35), we can see that it is capable of producing 1 G during any single application of force (braking, acceleration, or cornering).


traction circle 1


Point A clearly shows us that, while using .8 Gs for braking, only .5 Gs can be used for corning.


Let’s look at some examples showing how to use traction ratios effectively.

Imagine that a racecar is headed down a straight toward a corner that requires significant braking force.

If using the old method of racing, where the driver would use 100% of any single force, the brakes would be applied at 100% at the braking mark but then released at the turn-in point.

From that point, the driver would use 100% cornering force past the apex until he reached the exit point.

When the steering was unwound for the following straight, the throttle would be applied at 100%.

To be fair, this method of racing makes a lot of sense until you look at the forces mathematically.

In this example, the highest force generated in any direction is 1 G. As you can see by Figure 35, point A represents a combination of braking force and cornering force.

In this case the car is using both . 8 Gs of braking force and .5 Gs of cornering force, which doesn’t seem like much since the car can generate 1 G in any single direction.


The resulting combination of the steering and braking forces (.8G + .5G) reveals that the tire is actually using 1.3 Gs!

This is a larger force than can be used in a single direction. I cannot emphasize the value of this single concept enough.

Using these combination forces is the only way to reach your vehicle’s maximum traction potential.

The same concept applies to ratios of acceleration and corning. As you begin to unwind the steering wheel and cornering force decreases, more acceleration force becomes available.

This ties in directly with the ability to generate the highest possible corner exit speed.

Learning how to combine these forces plays a huge role in being the fastest guy on the track. Before you complain about inferior equipment, focus on the driver.

If the driver doesn’t understand the advantage of traction ratios and how to apply them… make him learn or get a new driver.


You now know everything you need to go win races. GO GET IT!

Thank you once again for taking the time to read this series of posts! As you can probably imagine, I worked very hard compiling this valuable information for you to consume. I would be very appreciative if you would share this series of posts with a friend.


Someone you know will love this! Who is it?
Bookmark the permalink.

Leave a Reply

Your email address will not be published.