Section Width645 mm (25.4")
Aspect Ratio37%
Rim Diameter14"
Overall Diameter833 mm (32.8")
Sidewall Height239 mm
Circumference2617 mm
645/37R14 — Buy Tires

Everything to know about the 645/37R14 tire size

Size geometry

A 645/37R14 tire has a 645mm section width and a 37% aspect ratio, mounted on a 14-inch rim. Sidewall height works out to 238.7mm (9.40") and overall outside diameter is 832.9mm (32.79"). At highway speed the tire completes about 382 revolutions per kilometre — your speedometer and odometer were calibrated against this number.

Direct substitute sizes

If 645/37R14 is unavailable, the closest same-diameter substitutes on the same rim are 635/38R14 and 655/36R14. 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 645/37R14 you can upsize to 655/34R15 (plus-one) to fit a larger wheel without changing the speedometer reading, or downsize to 635/40R13 (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 645/37R14 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 645/37R14

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