Fender Trimming Calculator

When fitting wider wheels and tires to a car, the new setup may protrude beyond the original fender line — and the Fender Trimming Calculator tells you exactly how much material needs to be removed to avoid rubbing. Enter your original tire width, aspect ratio, wheel diameter, wheel width, and offset, then your new setup's equivalent values and maximum steering lock angle. You'll get the fender trimming required in millimeters, plus outward and inward movement, overall diameter change, and clearance status.

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Maximum steering angle your vehicle can turn

Results

Fender Trimming Required

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Outward Movement

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Inward Movement

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Overall Diameter Change

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Clearance Status

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Frequently Asked Questions

What is fender trimming and when is it needed?

Fender trimming involves cutting or rolling the inner fender liner to create clearance for larger tires. It's needed when upgrading to wider tires or wheels with different offsets that would otherwise rub against the fender at full steering lock.

How do I measure my current wheel offset?

Wheel offset is usually stamped on the back of the wheel. Look for markings like 'ET40' which means 40mm positive offset. You can also measure from the wheel's mounting surface to the centerline of the wheel.

Will fender trimming affect my vehicle's safety or warranty?

Proper fender trimming typically doesn't affect safety as it only removes inner liner material. However, it may void certain warranty coverage, so check with your dealer before modifications.

Can I avoid fender trimming by using spacers instead?

Spacers push wheels outward which can actually make rubbing worse. They're useful for fine-tuning fitment but won't help with clearance issues that require trimming.

What's the difference between wheel offset and backspacing?

Offset is the distance from the wheel's mounting surface to its centerline (can be positive or negative). Backspacing is the distance from the mounting surface to the inner edge of the wheel (always positive).

How accurate is this fender trimming calculator?

This calculator provides estimates based on wheel and tire dimensions. Actual clearance can vary due to suspension geometry, ride height, and manufacturing tolerances. Always test fit before final installation.