Tire Size Calculator Compare

A tire size calculator that shows you the difference instead of listing it.

Put the size you run now next to the size you are about to buy. Both tires are drawn to one scale on one axle, so the change in diameter, width and stance is on the screen instead of in your head. Every number under the drawing is derived, not guessed: outer diameter, circumference, revolutions per mile, and how far your speedometer will read off once the new set is bolted on.

What it calculates:
• Same-scale silhouettes of both tires on a shared axle, with delta labels for diameter, width and aspect ratio
• Diameter delta in mm, inches and percent, with a warning the moment you cross the 3 percent tolerance
• Speedometer and odometer error: indicated 60 against actual 62.1, plus readings at 30, 50 and 70
• Ride height and section width change per side — the numbers behind rubbing, poke and arch clearance
• Revolutions per mile for both sizes
• Load index and speed rating tables with search
• Wheel offset calculator: rim width and ET to backspacing, poke or tuck

Metric or flotation input, metric or imperial output. Dial in 265/70R17 or 33x12.50R17, read millimetres or inches, mph or km/h — switch units and every value recalculates on the spot.

The garage keeps your setups. Name a tire size comparison, save it, open it again next season: stock against new, summer against winter, one truck or five. It opens offline and survives a restart.

Built for plus sizing a daily driver, for truck and 4x4 owners going up a size, and for anyone standing in front of a tire rack with a phone, doing wheel size calculator math that has to be right the first time.

The load index tables and the wheel offset calculator open after a short video. No subscription, no purchase, nothing to restore.

Works fully offline. No account, no sign up: the size reference and every calculation run on your device, so the app still works in a shop with no signal and nothing leaves your phone.

Set both sizes, tap Compare, read the numbers.

Recent changes:
Two tire sizes, one axle, one scale. Diameter delta in mm, inches and percent, with a warning when the new set crosses the 3 percent tolerance. Speedometer and odometer error at 30, 50, 60 and 70. Ride height and section width per side. Revolutions per mile for both sizes.

Save any comparison to the garage and open it again offline. Load index and speed rating tables and a wheel offset calculator with backspacing, poke and tuck are in there too.