Section Width505 mm (19.9")
Aspect Ratio138%
Rim Diameter20"
Overall Diameter1902 mm (74.9")
Sidewall Height697 mm
Circumference5975 mm
505/138R20 — Buy Tires

Everything to know about the 505/138R20 tire size

Size geometry

A 505/138R20 tire has a 505mm section width and a 138% aspect ratio, mounted on a 20-inch rim. Sidewall height works out to 696.9mm (27.44") and overall outside diameter is 1901.8mm (74.87"). At highway speed the tire completes about 167 revolutions per kilometre — your speedometer and odometer were calibrated against this number.

Direct substitute sizes

If 505/138R20 is unavailable, the closest same-diameter substitutes on the same rim are 495/141R20 and 515/135R20. 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 505/138R20 you can upsize to 515/133R21 (plus-one) to fit a larger wheel without changing the speedometer reading, or downsize to 495/143R19 (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 505/138R20 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 505/138R20

tire_size.no_vehicles_found