The calculators owners actually reach for — all in one place.
Save your disks and test any tyre against them for a proper, safe fit.
See rolling-diameter change and exactly how far your speedo reads off.
Work out offset, poke and fender clearance before you buy.
Store your front and rear disks once, then run any tyre size against them. No more spreadsheet, no more third-party calculators.
Every calculator shows a diagram, so you can see the change — offset, poke, diameter — and trust the figure before you commit.
Factory staggered fitments for the 987, so “vs OEM” actually means your car.
981 factory wheel and tyre specs built in, ready to compare against.