Section Width125 mm (4.9")
Aspect Ratio309%
Rim Diameter42"
Overall Diameter1839 mm (72.4")
Sidewall Height386 mm
Circumference5778 mm
125/309R42 — Buy Tires

Everything to know about the 125/309R42 tire size

Size geometry

A 125/309R42 tire has a 125mm section width and a 309% aspect ratio, mounted on a 42-inch rim. Sidewall height works out to 386.3mm (15.21") and overall outside diameter is 1839.3mm (72.41"). At highway speed the tire completes about 173 revolutions per kilometre — your speedometer and odometer were calibrated against this number.

Direct substitute sizes

If 125/309R42 is unavailable, the closest same-diameter substitutes on the same rim are 115/336R42 and 135/286R42. 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 125/309R42 you can upsize to 135/277R43 (plus-one) to fit a larger wheel without changing the speedometer reading, or downsize to 115/347R41 (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 125/309R42 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 125/309R42

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