Wheelia - Wheel Fitment Calc

"If I fit this wheel, how much room is left before it reaches the fender?" This is a tool for finishing that calculation before you buy.

■ Fitment (the heart of the app)

Enter your current wheel (rim diameter, rim width, offset, tire size) and the gap you measured from the fender. Enter the wheel you are considering, and you get:

- how many mm it moves outward
- what the gap becomes after the change

The result is worked out as a difference from your measured gap, so small errors in the fixed dimensions have little effect on the answer.

You can also work backwards from a target - flush with the fender, or 5 mm of gap left - and get:

- the offset you need
- the spacer thickness, if you keep the wheel you already have

■ Protrusion is shown separately for the tire and the wheel

Under the Japanese regulation on protruding rotating parts, neither the tire nor the wheel may sit outside the fender, within an arc 30 degrees forward and 50 degrees rearward of the vertical plane through the axle centre.

The revision dated 22 June 2017 stopped counting only two things as protrusion: the letters and markings on the sidewall, and the protective band and ribs where they stand less than 10 mm proud of the sidewall face. It does not mean the widest part of the tire, or the wheel, may sit up to 10 mm outside the fender.

This app shows how far the tire face and the wheel face each sit out, as two separate figures. When the tire is stretched so that the rim becomes the outermost face, the app also says that the revision above does not apply at all.

Note: this app does not decide whether a vehicle passes inspection. The applicable conditions and the final judgement rest with the inspection. Use it to check the numbers.

■ The other calculations

Tire size compare - overall diameter, circumference, ride height change and speedometer error. It also gives the true speed at a reading you choose.

Plus sizing - how the tire width changes when the rim width differs from the standard, shown as a range because it varies by model rather than as a single figure. It also shows the usual approximate rim range.

Camber - how far the top edge moves inward and the bottom edge moves outward at a given angle.

Bore and PCD - the hub ring thickness (one side) from the wheel bore and the vehicle hub. It warns when the two PCD values are close enough to be confused, such as 114.3 and 112.

Load index - the capacity per tire from the index, checked against the axle weight.

My wheels - save your current setup and the ones you are considering, with a name. Up to three without the purchase.

■ About the figures

What is built in is only the kind of number that does not change: unit definitions (1 inch = 25.4 mm), geometry, and standard tables (load index). Prices and labour rates, which go out of date quickly, are not part of it.

Where a value is only an estimate, it is labelled as such and shown as a range.

■ How it runs

- No connection is needed. Everything is calculated on the device.
- Saved data stays on the device and is not sent anywhere.
- Available in Japanese, English, Spanish, Portuguese, French, German, Korean and Chinese.

■ Ads and the purchase

**Every calculation is free.** The fitment result, the table by offset, the cross-section drawing and how far the inner face moves toward the suspension are all there without paying, and without watching anything.

A small banner sits at the top of the screen. There is no full-screen ad that interrupts you.

- Watch one short video and the ads go away for 60 minutes (nothing plays unless you tap it)
- The one-time purchase stops the ads for good and takes the saving slots to 50

It is a single payment.

■ What it does not have

There is no database that gives you the factory wheel size when you pick a car model. Take the figures from the markings on the wheel and the sidewall of the tire.

Recent changes:
First release. Work out how far the wheel moves outward and how much room is left to the fender. Includes the regulation figures for tire and wheel separately, reverse calculation from a target flush, an offset-by-offset list, a cross-section view, tire size comparison, plus sizing, camber, hub bore and PCD, and load index. All calculations run on your device.