Fitment Guides
What Wheel Offset Changes — And What A Visualiser Cannot Show
Understand positive and negative wheel offset, how ET changes wheel position, and why a visual preview cannot confirm mechanical clearance.
What Wheel Offset Changes
Wheel offset determines where the wheel sits relative to the hub. It is normally marked with an ET number measured in millimetres. Changing offset moves the complete wheel-and-tyre package inward or outward, even when the wheel diameter stays the same.
A visualiser can suggest whether a more flush or tucked position suits the car, but it cannot measure the clearance behind the wheel or predict every effect of a different offset.
Positive, Zero And Negative Offset
Positive offset means the mounting face sits towards the outside face of the wheel. This generally positions more of the wheel inward towards the suspension. Most modern road cars use positive offset. Zero offset places the mounting face on the wheel's centre line. Negative offset places it towards the inner side, pushing more of the wheel outward.
The number is not a quality score. ET45 is not inherently better than ET35; each describes a different position.
How Offset Changes The Outer Position
If wheel width stays identical, reducing positive offset by 10 mm moves the wheel approximately 10 mm farther outward. Increasing positive offset by 10 mm moves it approximately 10 mm inward.
Wheel width complicates the comparison. A wider wheel adds material to both sides of its centre line, so you must calculate inner and outer position using both width and offset.
If The Wheel Sits Too Far Out
- Tyre contact with the outer arch or liner
- Contact during steering or suspension compression
- Excess spray outside the bodywork
- Changes to steering feel and suspension leverage
- A setup outside legal or insurance requirements
A stationary photograph cannot show what happens when the suspension compresses or the steering reaches full lock.
If The Wheel Sits Too Far In
- Contact with struts, springs or suspension arms
- Reduced brake-caliper clearance
- Contact with the inner arch liner
- A visibly tucked appearance
- Insufficient space for balancing weights
Physical clearance must be checked on the exact car. Trim level, brake package and suspension changes can alter the available space.
What A Visualiser Can And Cannot Show
A preview can help you judge whether the wheel face appears too recessed or unnaturally far outside the body. It cannot confirm the measured offset, inner clearance, clearance at full lock, suspension travel, tyre coverage, hub fit or load suitability.
Treat stance in a generated image as styling guidance only.
Offset Checklist
- Confirm the factory wheel width and ET.
- Confirm the proposed wheel width and ET.
- Calculate both inner and outer position changes.
- Check suspension, brake and arch clearance.
- Confirm the correct centre bore and mounting hardware.
- Check tyre width and profile as part of the complete package.
- Ask a qualified fitter to verify anything uncertain.
Offset is one part of fitment, not a standalone approval. A wheel still needs the correct PCD, centre bore, load rating, diameter, width and tyre specification.