How to Calculate Steering Ratio?

The steering ratio is calculated by dividing the total degrees the steering wheel is turned by the average number of degrees the front wheels turn.

## Understanding Steering Ratio

Steering ratio is a fundamental specification in a vehicle's steering system. It indicates how many degrees the steering wheel must be turned to make the road wheels turn one degree. A higher ratio means you turn the steering wheel more for a given amount of wheel turn, typically resulting in lighter steering effort but requiring more turns for sharp corners. A lower ratio provides quicker steering response but can feel heavier.

In most passenger cars, the steering ratio typically falls **between 12:1 and 20:1**.

## The Calculation

To calculate the steering ratio, you need two key measurements:

1.  The total angle the steering wheel is rotated (in degrees).
2.  The angle the front road wheels turn (in degrees).

Due to **Ackermann steering geometry**, which ensures the inner wheel turns more sharply than the outer wheel during a turn, you must calculate the *average* turning angle of the front wheels.

The formula derived from this concept is:

**Steering Ratio = (Steering Wheel Turn Angle) / (Average Front Wheel Turn Angle)**

Where:
Average Front Wheel Turn Angle = (**(Inner Wheel Turn Angle + Outer Wheel Turn Angle) / 2**)

## Example Calculation

Let's use the example provided to illustrate this calculation:

*   Steering wheel turn: **540 degrees** (which is one and a half turns)
*   Inner front wheel turn: **35 degrees**
*   Outer front wheel turn: **30 degrees**

1.  **Calculate the average front wheel turn angle:**
    (35 degrees + 30 degrees) / 2 = 65 degrees / 2 = **32.5 degrees**

2.  **Calculate the steering ratio:**
    540 degrees / 32.5 degrees = **16.615...**

Therefore, the steering ratio in this example is approximately **16.6:1**. This means for every 16.6 degrees the steering wheel is turned, the front wheels (on average) turn 1 degree.

This calculation method allows you to determine the mechanical advantage and responsiveness of a vehicle's steering system.