Section Width505 mm (19.9")
Aspect Ratio49%
Rim Diameter18"
Overall Diameter952 mm (37.5")
Sidewall Height247 mm
Circumference2991 mm
505/49R18 — Buy Tires

Everything to know about the 505/49R18 tire size

Size geometry

A 505/49R18 tire has a 505mm section width and a 49% aspect ratio, mounted on a 18-inch rim. Sidewall height works out to 247.4mm (9.74") and overall outside diameter is 952.1mm (37.48"). At highway speed the tire completes about 334 revolutions per kilometre — your speedometer and odometer were calibrated against this number.

Direct substitute sizes

If 505/49R18 is unavailable, the closest same-diameter substitutes on the same rim are 495/50R18 and 515/48R18. 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 505/49R18 you can upsize to 515/46R19 (plus-one) to fit a larger wheel without changing the speedometer reading, or downsize to 495/53R17 (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 505/49R18 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 505/49R18

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