225/45R19 Tire Size in Inches

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

225/45R19
27.0" tall × 8.9" wide
On a 19-inch wheel · roughly 27.0x8.9R19 in flotation sizing
MeasurementInchesMillimetres
Overall diameter26.97685
Section width8.86225
Sidewall height3.99101.2
Wheel diameter19483
Circumference84.72152
Revolutions per mile748 (465 per km)

What 225/45R19 means

225 is the section width in millimetres (8.9 in). 45 is the aspect ratio: the sidewall is 45% as tall as the tire is wide, which works out to 101.2 mm or 4.0 in. R19 is a radial tire for a 19-inch wheel.

Overall diameter is the wheel plus two sidewalls: 19 + 2 × 3.99 = 27.0 inches. These are the nominal dimensions every maker builds to; a real 225/45R19 can measure a few tenths of an inch differently by model and inflation.

Closest equivalent sizes

Common sizes within the usual 3% of 225/45R19's overall diameter. Confirm load index, speed rating and rim width before swapping.

SizeDiameterWidthChangeSpeedometer at 60
215/65R16 new wheels 27.0 in 8.5 in +0.1% really 60.1 mph
255/35R20 new wheels 27.0 in 10.0 in +0.2% really 60.1 mph
255/40R19 27.0 in 10.0 in +0.2% really 60.1 mph
255/45R18 new wheels 27.0 in 10.0 in +0.2% really 60.1 mph
225/50R18 new wheels 26.9 in 8.9 in -0.4% really 59.7 mph
215/70R15 new wheels 26.9 in 8.5 in -0.5% really 59.7 mph

Speedometer if you switch to 255/40R19

Your speedometer stays calibrated for 225/45R19. With a taller tire you travel faster than it shows.

Speedometer readsTrue speed
30 mph30.1 mph
45 mph45.1 mph
55 mph55.1 mph
65 mph65.1 mph
75 mph75.2 mph
Compare 225/45R19 with any size →

Shop 225/45R19 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 225/45R19 tire is 27.0 inches (685 mm) tall overall. That is the 19-inch wheel plus two sidewalls of 4.0 inches each (45% of the 225 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 225 mm, or 8.9 inches, measured sidewall to sidewall on the recommended rim width. The tread itself is narrower than that. In flotation sizing, 225/45R19 is roughly a 27.0x8.9R19.

215/65R16 is the closest common size, at +0.1% overall diameter (27.0 in against 27.0 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 748 revolutions per mile (465 per kilometre), from its 27.0-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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Other 19-inch sizes

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