Tire Size Calculator: Car tool

Spectre Team

About this app

Will the new wheels fit?

Enter the tire and wheel you run now and the ones you are considering. The app draws both to scale, one over the other, from the same hub mounting face — so you can see how much further the new rim pokes out, how much closer it sits to the strut, and how much taller the whole wheel becomes.

THE DRAWING
Both wheels are drawn in cross-section on a shared axis, with the hub mounting face as the reference line. Pinch to zoom in up to 6x: the rim opens out into a real flange-and-drop-centre profile, a ruler appears along the top, and every dimension gets its own callout — rim width, section width, offset, backspace, and the gap between the two rims inside and out.

SIXTEEN MEASUREMENTS
Old and new side by side, each row with the difference:
• Disk width, tire width, tire height
• Overall diameter and circumference
• Poke, inset, backspace
• Speed error, plus what your speedometer will read at two speeds you pick
• Ride height gain and arch gap loss
• Suspension clearance, fender clearance, scrub radius

VEHICLE CATALOG
Don't know your factory sizes? Choose a make, a year and a model, and the app lists the wheel sets the car was sold with — staggered sets included — along with its spec sheet: generation, body, engine, power, bolt pattern, PCD, stud holes, centre bore and tire pressures. Tap a set to drop it straight into the comparison.

UP TO SIX SETUPS
Line up six wheels at once and swipe between them. Every setup holds a front and a rear axle, so staggered fitments stay staggered instead of being averaged away.

BOTH NOTATIONS
ISO metric (205/55 R16) and LT high flotation (33x12.50 R15).

YOUR UNITS, YOUR LANGUAGE
Millimetres or inches, km/h or mph. English, Русский, Italiano, Deutsch, Français, Čeština, Español, עברית.

SHARE IT
One tap turns the drawing and the full comparison table into a single image — send it to a friend, a forum thread or your fitter.

No ads, no sign-up. The maths runs on your device; only the vehicle catalog needs a connection.

Ratings and reviews

Great app, I wish the images of the tyre/wheel were bigger or could zoom in.

For deciding what tire and wheel combination to use for my cars - absolutely perfect. For me this is just a gorgeous app - Very simple to use and explains everything you need to know. I've personally used this app for a couple of years and I think there's nothing really more suited for the task.

What this needs to be complete, is a side profile view like Aimen RG's Tire Size Calculator app. Also could use configurable colors for both the tires and wheels, so I can tell which tire goes to which wheel when comparing close sizes. Although the update seems to add additional sizes you can compare with, you can only compare to the original and not with your other sizes.

What’s new

Zoom functionality has been added to the wheel display.