Section Width125 mm (4.9")
Aspect Ratio38%
Rim Diameter18"
Overall Diameter552 mm (21.7")
Sidewall Height48 mm
Circumference1735 mm
125/38R18 — Buy Tires

Everything to know about the 125/38R18 tire size

Size geometry

A 125/38R18 tire has a 125mm section width and a 38% aspect ratio, mounted on a 18-inch rim. Sidewall height works out to 47.5mm (1.87") and overall outside diameter is 552.2mm (21.74"). At highway speed the tire completes about 576 revolutions per kilometre — your speedometer and odometer were calibrated against this number.

Direct substitute sizes

If 125/38R18 is unavailable, the closest same-diameter substitutes on the same rim are 115/41R18 and 135/35R18. 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 125/38R18 you can upsize to 135/26R19 (plus-one) to fit a larger wheel without changing the speedometer reading, or downsize to 115/52R17 (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 125/38R18 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 125/38R18

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