Section Width645 mm (25.4")
Aspect Ratio63%
Rim Diameter12"
Overall Diameter1118 mm (44.0")
Sidewall Height406 mm
Circumference3511 mm
645/63R12 — Buy Tires

Everything to know about the 645/63R12 tire size

Size geometry

A 645/63R12 tire has a 645mm section width and a 63% aspect ratio, mounted on a 12-inch rim. Sidewall height works out to 406.4mm (16.00") and overall outside diameter is 1117.5mm (44.00"). At highway speed the tire completes about 285 revolutions per kilometre — your speedometer and odometer were calibrated against this number.

Direct substitute sizes

If 645/63R12 is unavailable, the closest same-diameter substitutes on the same rim are 635/64R12 and 655/62R12. Both keep your speedometer reading within 1% — safe for daily use, ABS, and stability control. Always verify load and speed ratings before swapping.

Plus / minus sizing options

For a 645/63R12 you can upsize to 655/60R13 (plus-one) to fit a larger wheel without changing the speedometer reading, or downsize to 635/66R11 (minus-one) for a softer ride or winter setup. Both stay inside the Âą3% diameter tolerance that ABS and TPMS systems expect.

Vehicle compatibility

0 vehicles in our database run the 645/63R12 tire size from the factory. Aftermarket fitment depends on rim width, offset, and clearance — match these specs to your wheel before purchasing tires.

Vehicles Using 645/63R12

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