Wheel Offset Calculator
Compare your current wheel setup to a new width and offset to understand how far the wheel will move relative to the suspension and fender.
How to Use This Calculator
Gather your current wheel specs
Wheel width is measured bead-to-bead in inches. Offset is printed on the wheel hub (e.g., ET35).
Enter the new wheel specs
Type the width and offset of the wheels you plan to install. The calculator compares them to your current setup.
Review inner and outer changes
Ensure the inner clearance doesn’t reduce enough to cause rubbing, and the outer poke stays within your fender limits.
Formula
Inner Change = ΔOffset + (ΔWidth ÷ 2)
Outer Change = (ΔWidth ÷ 2) − ΔOffset
ΔWidth: (New Width − Old Width) converted to millimeters
ΔOffset: New Offset − Old Offset
Example: Old 8" +35, New 9.5" +22 → ΔWidth = 1.5" = 38.1 mm → ΔOffset = -13 mm → Inner = -13 + 19.05 = 6.05 mm closer to suspension → Outer = 19.05 − (-13) = 32.05 mm further outward.
About the Wheel Offset Calculator
Wheel width and offset changes affect suspension clearance, fender fitment, and track width. This calculator shows the difference so you can choose spacers or wheel sizes confidently.
When to Use This Calculator
- Wheel upgrades: Evaluate fitment before buying new wheels or spacers.
- Brake upgrades: Ensure new calipers will clear inside the wheel barrel.
- Stance adjustments: Plan poke and flush fitment for show cars.
- Suspension tuning: Check how camber changes might interact with wheel position.
Why Use Our Calculator?
- ✅ Clear results: Inner and outer movement in both millimeters and inches.
- ✅ Track width insight: Shows total change to help maintain alignment geometry.
- ✅ Quick experiments: Try multiple wheel combos without complicated math.
- ✅ Mobile friendly: Use while shopping or at the alignment rack.
Common Applications
Wheel retailers: Check fitment when recommending new wheel packages.
Autocross/track drivers: Balance grip gains with fender clearance.
Off-road builds: Assess wider wheels and spacers for stability.
Tips for Best Results
- Measure actual clearance to brake calipers, struts, and fender edges before making drastic changes.
- Consider tire width—wider tires can rub even if the wheel itself clears.
- Include alignment changes; more negative camber pulls the top of the wheel inward.
- Use quality spacers and extended studs when pushing wheels outward for proper engagement.
Frequently Asked Questions
What does a positive inner change mean?
Positive inner clearance change means the wheel moves closer to the suspension or brake components, reducing clearance. Ensure there’s enough space to avoid rubbing.
Can I use negative offsets?
Yes. Enter negative numbers for deep dish wheels. The math handles positive and negative offsets automatically.
Does tire size affect the calculation?
The tool focuses on wheel changes. Wider or taller tires may extend beyond the wheel lip, so add a safety margin for tire bulge.
How accurate is this compared to CAD?
It uses simplified geometry that matches standard fitment calculators. For extreme setups, 3D scanning or measuring with the wheel mounted is recommended.