Section Width645 mm (25.4")
Aspect Ratio38%
Rim Diameter27"
Overall Diameter1176 mm (46.3")
Sidewall Height245 mm
Circumference3695 mm
645/38R27 — Buy Tires

Everything to know about the 645/38R27 tire size

Size geometry

A 645/38R27 tire has a 645mm section width and a 38% aspect ratio, mounted on a 27-inch rim. Sidewall height works out to 245.1mm (9.65") and overall outside diameter is 1176.0mm (46.30"). At highway speed the tire completes about 271 revolutions per kilometre — your speedometer and odometer were calibrated against this number.

Direct substitute sizes

If 645/38R27 is unavailable, the closest same-diameter substitutes on the same rim are 635/39R27 and 655/37R27. 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 645/38R27 you can upsize to 655/35R28 (plus-one) to fit a larger wheel without changing the speedometer reading, or downsize to 635/41R26 (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 645/38R27 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 645/38R27

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