255/85R16 Tire Size in Inches

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

255/85R16
33.1" tall × 10.0" wide
On a 16-inch wheel · roughly 33.1x10.0R16 in flotation sizing
MeasurementInchesMillimetres
Overall diameter33.07840
Section width10.04255
Sidewall height8.53216.8
Wheel diameter16406
Circumference103.92639
Revolutions per mile610 (379 per km)

What 255/85R16 means

255 is the section width in millimetres (10.0 in). 85 is the aspect ratio: the sidewall is 85% as tall as the tire is wide, which works out to 216.8 mm or 8.5 in. R16 is a radial tire for a 16-inch wheel.

Overall diameter is the wheel plus two sidewalls: 16 + 2 × 8.53 = 33.1 inches. These are the nominal dimensions every maker builds to; a real 255/85R16 can measure a few tenths of an inch differently by model and inflation.

Closest equivalent sizes

Common sizes within the usual 3% of 255/85R16's overall diameter. Confirm load index, speed rating and rim width before swapping.

SizeDiameterWidthChangeSpeedometer at 60
275/60R20 new wheels 33.0 in 10.8 in -0.2% really 59.9 mph
275/70R18 new wheels 33.2 in 10.8 in +0.3% really 60.2 mph
305/55R20 new wheels 33.2 in 12.0 in +0.4% really 60.3 mph
285/75R16 32.8 in 11.2 in -0.7% really 59.6 mph
305/70R16 32.8 in 12.0 in -0.8% really 59.5 mph
305/45R22 new wheels 32.8 in 12.0 in -0.8% really 59.5 mph

Speedometer if you switch to 285/75R16

Your speedometer stays calibrated for 255/85R16. With a shorter tire you travel slower than it shows.

Speedometer readsTrue speed
30 mph29.8 mph
45 mph44.7 mph
55 mph54.6 mph
65 mph64.5 mph
75 mph74.5 mph
Compare 255/85R16 with any size →

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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 255/85R16 tire is 33.1 inches (840 mm) tall overall. That is the 16-inch wheel plus two sidewalls of 8.5 inches each (85% 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, 255/85R16 is roughly a 33.1x10.0R16.

275/60R20 is the closest common size, at -0.2% overall diameter (33.0 in against 33.1 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 610 revolutions per mile (379 per kilometre), from its 33.1-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 16-inch sizes

195/55R16 195/60R16 195/65R16 205/50R16 205/55R16 205/60R16 205/65R16 215/55R16 215/60R16 215/65R16 215/70R16 215/85R16 225/50R16 225/55R16 225/60R16 225/65R16 225/70R16 225/75R16 235/60R16 235/65R16 235/70R16 235/75R16 235/85R16 245/70R16 245/75R16 255/65R16 255/70R16 265/70R16 265/75R16 285/75R16 205/45R16 275/70R16 305/70R16 315/75R16