Use this calculator to understand how changing your wheel width and offset will affect your wheel's position relative to your vehicle's fender and suspension components. This helps prevent rubbing and achieve your desired stance.
Current Wheel Specifications
New Wheel Specifications
Understanding Wheel Offset
Wheel offset is a critical measurement that determines how your wheels sit in relation to your vehicle's fenders and suspension. It's the distance from the wheel's mounting surface (where it bolts to the hub) to the true centerline of the wheel.
Types of Offset:
Positive Offset: The mounting surface is towards the outside of the wheel. This pulls the wheel further *into* the fender well, closer to the suspension. Most front-wheel-drive cars and newer rear-wheel-drive cars have positive offset.
Negative Offset: The mounting surface is towards the inside of the wheel. This pushes the wheel further *out* from the fender well, away from the suspension. This is common on older vehicles, trucks, and for a "deep dish" look.
Zero Offset: The mounting surface is exactly at the centerline of the wheel.
Why is Offset Important?
When changing wheels, especially to a different width or diameter, understanding offset is crucial for several reasons:
Fender Clearance: Incorrect offset can cause the tire to rub against the fender lip when turning or going over bumps.
Suspension Clearance: Too much positive offset (or insufficient negative offset for a wider wheel) can cause the inner edge of the tire or wheel to rub against suspension components (struts, control arms).
Brake Clearance: Some brake calipers, especially larger aftermarket ones, require specific offset to clear the wheel spokes.
Handling Characteristics: Changing the offset significantly can alter the scrub radius, which affects steering feel and handling.
Aesthetics: Offset plays a major role in how "flush" your wheels sit with the fenders, contributing to the overall look of your vehicle.
How to Use the Calculator:
Enter the width (in inches) and offset (in millimeters) of your current wheels, then do the same for the new wheels you are considering. The calculator will then show you:
Outer Edge Movement: How much further out or in the new wheel's outer edge will be compared to your current setup. A positive value means it "pokes" out more, a negative value means it "tucks" in more.
Inner Edge Movement: How much further away from or closer to your suspension components the new wheel's inner edge will be. A positive value means more inner clearance, a negative value means less.
Backspacing: The distance from the mounting surface to the inner edge of the wheel for both your current and new wheels. This is another critical measurement for inner clearance.
Always double-check measurements and consider professional advice when making significant changes to wheel and tire setups.