255/75R15 tire size in inches

A 255/75R15 tire measures

30.1" tall × 10.0" wide

7.53" sidewall on a 15" wheel. 671 revolutions per mile.

255/75R15 means a tire 255 mm wide, with sidewalls 75% as tall as the tire is wide (191 mm), radial construction (R), for a 15 inch wheel.

30.1"15" rim7.5"10.0" wide
255/75R15: 30.1 inches tall, 10.0 inches wide, on a 15 inch rim, drawn to scale

255/75R15 specs

Overall diameter (height)30.06 inches (764 mm)
Section width10.04 inches (255 mm)
Sidewall height7.53 inches (191 mm)
Wheel (rim) diameter15 inches
Circumference94.4 inches (2,399 mm)
Revolutions per mile671
Revolutions per kilometer417
Approximate rim width7.0" to 8.5"
In inches (flotation style)30.1x10.0R15
Aspect ratio75%

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 255/75R15 on a 15" wheel

These 15" sizes are within 3% of 255/75R15's overall diameter, the range most tire shops treat as interchangeable.

SizeDiameterWidthDifferenceReal speed at 60
225/85R1530.06"8.86"0.0%60.0 mphCompare
30x9.50R1530.00"9.50"−0.2%59.9 mphCompare
275/70R1530.16"10.83"+0.3%60.2 mphCompare
235/80R1529.80"9.25"−0.9%59.5 mphCompare
245/80R1530.43"9.65"+1.2%60.7 mphCompare
265/70R1529.61"10.43"−1.5%59.1 mphCompare
285/65R1529.59"11.22"−1.6%59.1 mphCompare
245/75R1529.47"9.65"−2.0%58.8 mphCompare
265/75R1530.65"10.43"+2.0%61.2 mphCompare
285/70R1530.71"11.22"+2.2%61.3 mphCompare
215/85R1529.39"8.46"−2.2%58.7 mphCompare
235/85R1530.73"9.25"+2.2%61.3 mphCompare

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

SizeWheelDiameterDifference
255/80R1414"30.06"0.0%Compare
255/70R1616"30.06"0.0%Compare
255/65R1717"30.05"0.0%Compare
255/60R1818"30.05"0.0%Compare
255/55R1919"30.04"−0.1%Compare
275/65R1616"30.07"+0.1%Compare
255/50R2020"30.04"−0.1%Compare
255/45R2121"30.04"−0.1%Compare
255/40R2222"30.03"−0.1%Compare
235/65R1818"30.03"−0.1%Compare
255/30R2424"30.02"−0.1%Compare
285/45R2020"30.10"+0.1%Compare

One size up or down

Compare 255/75R15 with another size

With 265/75R15 tires, when your speedometer says 60 mph you are really going

61.2 mph

265/75R15 is +0.59 inches (+2.0%) in overall diameter. That is within the 3% most shops and makers allow.

255/75R15265/75R15Difference%
Overall diameter30.06"30.65"+0.59"+2.0%
Section width10.04"10.43"+0.39"+3.9%
Sidewall height7.53"7.82"+0.30"+3.9%
Circumference94.43"96.29"+1.86"+2.0%
Revolutions per mile670.9658.0−12.9−1.9%

Questions

How tall is a 255/75R15 tire?
A 255/75R15 tire is 30.1 inches tall (764 mm), calculated from the size. It is 10.0 inches wide with 7.5 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
What does 255/75R15 mean?
255/75R15 means a tire 255 mm wide, with sidewalls 75% as tall as the tire is wide (191 mm), radial construction (R), for a 15 inch wheel.
How many revolutions per mile does a 255/75R15 tire make?
About 671 revolutions per mile, based on a circumference of 94.4 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
What rim width fits a 255/75R15 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 225/85R15 instead of 255/75R15?
225/85R15 is 0.00 inches (0.0%) in overall diameter, so at an indicated 60 mph you would be doing 60.0 mph. Differences under 3% are usually fine, but check clearance, load index and your vehicle's placard.

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