255/50R19 Tire Size in Inches

Diameter, width, sidewall and the closest equivalent sizes, computed from the size code.

255/50R19
29.0" tall × 10.0" wide
On a 19-inch wheel · roughly 29.0x10.0R19 in flotation sizing
MeasurementInchesMillimetres
Overall diameter29.04738
Section width10.04255
Sidewall height5.02127.5
Wheel diameter19483
Circumference91.22317
Revolutions per mile695 (432 per km)

What 255/50R19 means

255 is the section width in millimetres (10.0 in). 50 is the aspect ratio: the sidewall is 50% as tall as the tire is wide, which works out to 127.5 mm or 5.0 in. R19 is a radial tire for a 19-inch wheel.

Overall diameter is the wheel plus two sidewalls: 19 + 2 × 5.02 = 29.0 inches. These are the nominal dimensions every maker builds to; a real 255/50R19 can measure a few tenths of an inch differently by model and inflation.

Closest equivalent sizes

Common sizes within the usual 3% of 255/50R19's overall diameter. Confirm load index, speed rating and rim width before swapping.

SizeDiameterWidthChangeSpeedometer at 60
255/45R20 new wheels 29.0 in 10.0 in -0.0% really 60.0 mph
255/55R18 new wheels 29.0 in 10.0 in +0.0% really 60.0 mph
255/40R21 new wheels 29.0 in 10.0 in -0.0% really 60.0 mph
255/60R17 new wheels 29.0 in 10.0 in +0.0% really 60.0 mph
235/65R17 new wheels 29.0 in 9.3 in -0.0% really 60.0 mph
255/65R16 new wheels 29.1 in 10.0 in +0.0% really 60.0 mph

Speedometer if you switch to 255/45R20

Your speedometer stays calibrated for 255/50R19. With a shorter tire you travel slower than it shows.

Speedometer readsTrue speed
30 mph30.0 mph
45 mph45.0 mph
55 mph55.0 mph
65 mph65.0 mph
75 mph75.0 mph
Compare 255/50R19 with any size →

Shop 255/50R19 tires

Check the load index and speed rating on your door-jamb placard before you buy, especially for LT tires used for towing.

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Frequently Asked Questions

A 255/50R19 tire is 29.0 inches (738 mm) tall overall. That is the 19-inch wheel plus two sidewalls of 5.0 inches each (50% of the 255 mm section width). Expect a real tire to measure within a few tenths of an inch of this, depending on the model and inflation.

The section width is 255 mm, or 10.0 inches, measured sidewall to sidewall on the recommended rim width. The tread itself is narrower than that. In flotation sizing, 255/50R19 is roughly a 29.0x10.0R19.

255/45R20 is the closest common size, at -0.0% overall diameter (29.0 in against 29.0 in). Most makers treat about 3% as the limit for a swap without speedometer or clearance problems, but always confirm load index, speed rating and wheel width before changing size.

About 695 revolutions per mile (432 per kilometre), from its 29.0-inch rolling diameter. Real-world figures run slightly higher because a loaded tire squats. This number is what your speedometer and odometer are calibrated against.

Last updated: October 2, 2026

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The full calculator compares up to three sizes with speedometer error, clearance change and a to-scale diagram.

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Other 19-inch sizes

225/40R19 225/45R19 225/55R19 235/35R19 235/40R19 235/45R19 235/50R19 235/55R19 245/35R19 245/40R19 245/45R19 245/50R19 245/55R19 255/35R19 255/40R19 255/45R19 255/55R19 265/50R19 275/35R19 275/40R19 275/45R19 285/45R19 275/55R19 285/40R19