245/45R19 Tire Size in Inches

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

245/45R19
27.7" tall × 9.6" wide
On a 19-inch wheel · roughly 27.7x9.6R19 in flotation sizing
MeasurementInchesMillimetres
Overall diameter27.68703
Section width9.65245
Sidewall height4.34110.2
Wheel diameter19483
Circumference87.02209
Revolutions per mile729 (453 per km)

What 245/45R19 means

245 is the section width in millimetres (9.6 in). 45 is the aspect ratio: the sidewall is 45% as tall as the tire is wide, which works out to 110.2 mm or 4.3 in. R19 is a radial tire for a 19-inch wheel.

Overall diameter is the wheel plus two sidewalls: 19 + 2 × 4.34 = 27.7 inches. These are the nominal dimensions every maker builds to; a real 245/45R19 can measure a few tenths of an inch differently by model and inflation.

Closest equivalent sizes

Common sizes within the usual 3% of 245/45R19's overall diameter. Confirm load index, speed rating and rim width before swapping.

SizeDiameterWidthChangeSpeedometer at 60
215/75R15 new wheels 27.7 in 8.5 in +0.1% really 60.0 mph
275/40R19 27.7 in 10.8 in -0.1% really 60.0 mph
245/50R18 new wheels 27.6 in 9.6 in -0.1% really 59.9 mph
245/40R20 new wheels 27.7 in 9.6 in +0.1% really 60.1 mph
225/60R17 new wheels 27.6 in 8.9 in -0.2% really 59.9 mph
225/55R18 new wheels 27.7 in 8.9 in +0.2% really 60.1 mph

Speedometer if you switch to 275/40R19

Your speedometer stays calibrated for 245/45R19. 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 mph74.9 mph
Compare 245/45R19 with any size →

Shop 245/45R19 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 245/45R19 tire is 27.7 inches (703 mm) tall overall. That is the 19-inch wheel plus two sidewalls of 4.3 inches each (45% of the 245 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 245 mm, or 9.6 inches, measured sidewall to sidewall on the recommended rim width. The tread itself is narrower than that. In flotation sizing, 245/45R19 is roughly a 27.7x9.6R19.

215/75R15 is the closest common size, at +0.1% overall diameter (27.7 in against 27.7 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 729 revolutions per mile (453 per kilometre), from its 27.7-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 245/50R19 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