Vehicle Turning Circle Calculator
*Note: Wall-to-wall calculations usually require adding front overhang distance, which varies by vehicle body design.
What is a Turning Circle?
A vehicle's turning circle is the diameter of the smallest circular path the outer-most part of the vehicle can travel when the steering wheel is at full lock. In automotive specifications, this is often divided into two categories: "Kerb-to-Kerb" and "Wall-to-Wall".
The Kerb-to-Kerb distance measures the path of the wheels, while Wall-to-Wall considers the overhang of the front bumper, making it a larger and more practical measurement for parking in tight spaces.
How is the Turning Circle Calculated?
The fundamental physics of vehicle steering relies on the geometry between the front and rear axles. For a standard car, the calculation follows the Ackermann steering principles. The basic formula used in this calculator is:
Diameter (D) = 2 × (Radius + (Track Width / 2))
Practical Example
Imagine a compact sedan with the following specs:
- Wheelbase: 2.65 meters
- Steering Angle: 38 degrees
- Track Width: 1.55 meters
First, we find the turning radius of the center of the front axle: 2.65 / sin(38°) ≈ 4.30m. Adding the half-track width to account for the outer wheel, the radius becomes roughly 5.07m. The total turning circle diameter would therefore be approximately 10.14 meters.
Factors That Affect Turning Ability
Several mechanical factors influence how tightly a vehicle can turn beyond just its physical dimensions:
- Steering Rack Ratio: How many turns of the steering wheel it takes to move the wheels from lock to lock.
- Drivetrain Layout: Front-wheel drive (FWD) vehicles often have larger turning circles than Rear-wheel drive (RWD) vehicles because the constant velocity (CV) joints in FWD cars limit how far the front wheels can pivot.
- Wheel Size: Larger wheels or wider tires may hit the inner wheel well, requiring manufacturers to limit the steering angle.