1. What is Scrub Radius?

Scrub radius is the distance between the center of the tire contact patch and the point where the steering axis intersects the ground. It's a critical parameter in vehicle suspension design that affects steering feel, stability, and tire wear.

2. How Does the Calculator Work?

The calculator uses the scrub radius formula:

Where:

• Steering Axis Offset at Ground — The lateral distance from the tire centerline to the steering axis intersection point with the ground (mm)

Explanation: The scrub radius directly equals the steering axis offset at ground level, representing the lever arm that creates steering feedback and affects vehicle handling characteristics.

3. Importance of Scrub Radius Calculation

Details: Proper scrub radius calculation is essential for optimizing vehicle handling, reducing torque steer, minimizing tire wear, and ensuring stable braking performance. It significantly influences steering feel and feedback to the driver.

4. Using the Calculator

Tips: Enter the steering axis offset at ground measurement in millimeters. The value must be positive and greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical scrub radius value?
A: Most vehicles have a scrub radius between 0-25 mm. Positive scrub radius is common in front-wheel drive vehicles, while rear-wheel drive vehicles often have negative scrub radius.

Q2: How does scrub radius affect braking?
A: Excessive scrub radius can cause brake pull or instability during braking due to unequal forces acting on the steering system.

Q3: Can scrub radius be adjusted?
A: Yes, through wheel offset changes, steering axis inclination adjustments, or changing wheel centerline position relative to the suspension components.

Q4: What are the effects of positive vs negative scrub radius?
A: Positive scrub radius tends to provide better steering feedback but may cause brake pull. Negative scrub radius offers more stability but can reduce steering feel.

Q5: How does scrub radius affect tire wear?
A: Improper scrub radius can cause accelerated tire wear, especially on the inner or outer edges of the tires, due to increased scrubbing action during steering.