Free tools

Wheel & tire fitment tools

Two free calculators for the fitment numbers that actually decide a setup — offset and backspacing, poke and clearance, tire diameter and speedometer error. No sign-up, runs in your browser.

Calculator

Wheel offset calculator

Convert offset (ET) to backspacing and back, add a spacer to see the effective offset, then compare your current wheel with a new one to see exactly how much it pokes out or moves toward the suspension — with a live cross-section diagram.

Open the calculator → Calculator

Tire size calculator

Compare two tire sizes for diameter, sidewall, circumference and revolutions per mile, see the speedometer error at a glance, and pick from a list of alternative sizes calculated to stay within the usual 3% guideline.

Open the calculator →

From your car to a setup you trust

The calculators answer two questions. Here is where they sit in the whole run, in order.

  1. Start with your vehicle. Find yours in the visualizer by vehicle. Each page lists the factory bolt pattern, center bore and OEM wheel sizes, so you start from published numbers rather than a forum post.
  2. Confirm the bolt pattern and center bore. If the wheel cannot bolt on, nothing else matters. Wheel bolt patterns explained shows how to read and measure yours, and the wheel fitment guide covers what comes after it — diameter, width, offset and brake clearance.
  3. Compare the offset. Put your current wheel next to the one you want in the wheel offset calculator. It converts offset and backspacing and shows, in millimeters, how much further the new wheel pokes out or moves in toward the suspension.
  4. Compare the tire size. A new wheel usually means a new tire. The tire size calculator compares overall diameter, sidewall and revolutions per mile, and reads out the speedometer error against the usual 3% guideline.
  5. See it on your car. The numbers show where the wheel sits; a render shows whether you like it. Open WheelPeek in your browser, add a photo and swap in real wheels — your first five renders need no account.

Start from your vehicle

Fourteen vehicles with a factory setup on file. Open the fitment page, or send the factory numbers straight into a calculator.

Factory figures are estimates compiled from published data and vary by trim, year and market — verify yours against the door-jamb sticker or the seller before ordering. The app itself works with a photo of any car, not just these fourteen.

Learn the numbers behind the tools

Wheel fitment guide

Diameter, width, offset and brake clearance — the numbers that decide if a wheel works.

Read the guide →

Wheel offset visualizer

Tuck, flush or poke — what offset does to your stance, and how to preview it on your car.

Read the guide →

Wheel bolt patterns explained

The first fitment gate — what 5x112 means and how to measure it before you shop.

Read the guide →

See these wheels on your own car

Numbers tell you where the wheel sits; a render tells you if you like it. Swap real wheels onto a photo of your car and get a photoreal render in about ten seconds.

Try WheelPeek free in your browser

No sign-up for your first 5 rendersNo credit card~10s per render