285/45R22 Tire Size in Inches

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

285/45R22
32.1" tall × 11.2" wide
On a 22-inch wheel · roughly 32.1x11.2R22 in flotation sizing
MeasurementInchesMillimetres
Overall diameter32.10815
Section width11.22285
Sidewall height5.05128.2
Wheel diameter22559
Circumference100.82561
Revolutions per mile628 (390 per km)

What 285/45R22 means

285 is the section width in millimetres (11.2 in). 45 is the aspect ratio: the sidewall is 45% as tall as the tire is wide, which works out to 128.2 mm or 5.0 in. R22 is a radial tire for a 22-inch wheel.

Overall diameter is the wheel plus two sidewalls: 22 + 2 × 5.05 = 32.1 inches. These are the nominal dimensions every maker builds to; a real 285/45R22 can measure a few tenths of an inch differently by model and inflation.

Closest equivalent sizes

Common sizes within the usual 3% of 285/45R22's overall diameter. Confirm load index, speed rating and rim width before swapping.

SizeDiameterWidthChangeSpeedometer at 60
275/65R18 new wheels 32.1 in 10.8 in -0.1% really 60.0 mph
255/75R17 new wheels 32.1 in 10.0 in -0.1% really 59.9 mph
255/70R18 new wheels 32.1 in 10.0 in -0.1% really 59.9 mph
275/70R17 new wheels 32.2 in 10.8 in +0.2% really 60.1 mph
305/50R20 new wheels 32.0 in 12.0 in -0.3% really 59.8 mph
275/55R20 new wheels 31.9 in 10.8 in -0.6% really 59.6 mph

Speedometer if you switch to 275/65R18

Your speedometer stays calibrated for 285/45R22. 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 285/45R22 with any size →

Shop 285/45R22 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 285/45R22 tire is 32.1 inches (815 mm) tall overall. That is the 22-inch wheel plus two sidewalls of 5.0 inches each (45% of the 285 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 285 mm, or 11.2 inches, measured sidewall to sidewall on the recommended rim width. The tread itself is narrower than that. In flotation sizing, 285/45R22 is roughly a 32.1x11.2R22.

275/65R18 is the closest common size, at -0.1% overall diameter (32.1 in against 32.1 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 628 revolutions per mile (390 per kilometre), from its 32.1-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 22-inch sizes

265/40R22 275/40R22 285/40R22 305/40R22 255/30R22 265/35R22 285/35R22 295/30R22 305/45R22