255/85R15 tire size in inches

A 255/85R15 tire measures

32.1" tall × 10.0" wide

8.53" sidewall on a 15" wheel. 629 revolutions per mile.

255/85R15 means a tire 255 mm wide, with sidewalls 85% as tall as the tire is wide (217 mm), radial construction (R), for a 15 inch wheel.

32.1"15" rim8.5"10.0" wide
255/85R15: 32.1 inches tall, 10.0 inches wide, on a 15 inch rim, drawn to scale

255/85R15 specs

Overall diameter (height)32.07 inches (814 mm)
Section width10.04 inches (255 mm)
Sidewall height8.53 inches (217 mm)
Wheel (rim) diameter15 inches
Circumference100.7 inches (2,559 mm)
Revolutions per mile629
Revolutions per kilometer391
Approximate rim width7.0" to 8.5"
In inches (flotation style)32.1x10.0R15
Aspect ratio85%

Calculated from the size. Real tires differ by brand, model and tread depth, typically by a few tenths of an inch.

Sizes that can replace 255/85R15 on a 15" wheel

These 15" sizes are within 3% of 255/85R15's overall diameter, the range most tire shops treat as interchangeable.

SizeDiameterWidthDifferenceReal speed at 60
32x11.50R1532.00"11.50"−0.2%59.9 mphCompare
285/75R1531.83"11.22"−0.7%59.6 mphCompare
275/80R1532.32"10.83"+0.8%60.5 mphCompare
265/80R1531.69"10.43"−1.2%59.3 mphCompare
245/85R1531.40"9.65"−2.1%58.7 mphCompare
265/85R1532.74"10.43"+2.1%61.3 mphCompare
275/75R1531.24"10.83"−2.6%58.5 mphCompare
285/80R1532.95"11.22"+2.8%61.7 mphCompare
33x12.50R1533.00"12.50"+2.9%61.7 mphCompare

Same height on other wheel sizes (plus and minus sizing)

SizeWheelDiameterDifference
255/80R1616"32.06"0.0%Compare
255/75R1717"32.06"0.0%Compare
275/65R1818"32.07"0.0%Compare
325/55R1818"32.07"0.0%Compare
255/70R1818"32.06"0.0%Compare
255/65R1919"32.05"0.0%Compare
255/60R2020"32.05"−0.1%Compare
255/55R2121"32.04"−0.1%Compare
255/50R2222"32.04"−0.1%Compare
285/45R2222"32.10"+0.1%Compare
295/65R1717"32.10"+0.1%Compare
255/40R2424"32.03"−0.1%Compare

One size up or down

Compare 255/85R15 with another size

With 265/85R15 tires, when your speedometer says 60 mph you are really going

61.3 mph

265/85R15 is +0.67 inches (+2.1%) in overall diameter. That is within the 3% most shops and makers allow.

255/85R15265/85R15Difference%
Overall diameter32.07"32.74"+0.67"+2.1%
Section width10.04"10.43"+0.39"+3.9%
Sidewall height8.53"8.87"+0.33"+3.9%
Circumference100.74"102.84"+2.10"+2.1%
Revolutions per mile628.9616.1−12.9−2.0%

Questions

How tall is a 255/85R15 tire?
A 255/85R15 tire is 32.1 inches tall (814 mm), calculated from the size. It is 10.0 inches wide with 8.5 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
What does 255/85R15 mean?
255/85R15 means a tire 255 mm wide, with sidewalls 85% as tall as the tire is wide (217 mm), radial construction (R), for a 15 inch wheel.
How many revolutions per mile does a 255/85R15 tire make?
About 629 revolutions per mile, based on a circumference of 100.7 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
What rim width fits a 255/85R15 tire?
Roughly 7.0" to 8.5". Check the tire maker's approved rim range for the exact model before buying wheels.
Can I use 32x11.50R15 instead of 255/85R15?
32x11.50R15 is −0.07 inches (−0.2%) in overall diameter, so at an indicated 60 mph you would be doing 59.9 mph. Differences under 3% are usually fine, but check clearance, load index and your vehicle's placard.

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