"In this section we are going to discuss vehicle dynamics. Vehicle dynamics is a term used to describe how a car responds to a drivers control inputs.

All cars respond to the drivers input following the laws of physics. The cars in the sim are designed to respond in the same way as real cars.

Your ability to get the car around the racetrack is dependant on the capability of the car but its even more dependant on your ability to control the car, having a good understand of how to control the car whether sim or real is essential to being a good driver.

Whether you're racing or simply driving to work there are three basic control inputs or commands a driver can use to make the car perform

• The gas pedal + clutch + shift pedal = Go
• Brake = Stop
• Steering wheel = Turn

Learning to effectively use the controls is the key to driving well, in fact its even more important in a Sim as the feedback you get is drastically less in the sim than in a real car, you have no seat-of the-pants forces to tell you the result of your inputs in the sim and have to rely on visual and limited steering feedback to asses the effectiveness of your actions, thus the more knowledge the driver has, the more efficient they will be in controlling the sim car.

All of the commands you give the car with these controls are transmitted into action through the tyres, understand how the tyres work is the first step.

The engineers at iRacing have been very careful to accurately replicate the way real tyres behave in the simulation.

There are three directional forces the tyre is subject to;

• Acceleration
• Braking
• Turning

The tyre's grip can be devoted to any one or a combination of these forces to accomplish a drivers command, a tyre interacts with the surface of the track by distortion of rubber moving over the surface, causing a small amount of slip, this slip referred to as the slip angle while cornering determines the effectiveness of the tyres contact patch.

Too much slip and you lose grip

Not enough and your below the potential of the tyres.

In part two of vehicle dynamics we'll take a look at how tyre grip is influenced by load transfer in your car and will show you some ways to practice what you have learned..."