185/70R15 tire size in inches

A 185/70R15 tire measures

25.2" tall × 7.3" wide

5.10" sidewall on a 15" wheel. 800 revolutions per mile.

185/70R15 means a tire 185 mm wide, with sidewalls 70% as tall as the tire is wide (130 mm), radial construction (R), for a 15 inch wheel.

25.2"15" rim5.1"7.3" wide
185/70R15: 25.2 inches tall, 7.3 inches wide, on a 15 inch rim, drawn to scale

185/70R15 specs

Overall diameter (height)25.20 inches (640 mm)
Section width7.28 inches (185 mm)
Sidewall height5.10 inches (130 mm)
Wheel (rim) diameter15 inches
Circumference79.2 inches (2,011 mm)
Revolutions per mile800
Revolutions per kilometer497
Approximate rim width5.0" to 6.5"
In inches (flotation style)25.2x7.3R15
Aspect ratio70%

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 185/70R15 on a 15" wheel

These 15" sizes are within 3% of 185/70R15's overall diameter, the range most tire shops treat as interchangeable.

SizeDiameterWidthDifferenceReal speed at 60
235/55R1525.18"9.25"−0.1%60.0 mphCompare
215/60R1525.16"8.46"−0.2%59.9 mphCompare
285/45R1525.10"11.22"−0.4%59.8 mphCompare
175/75R1525.33"6.89"+0.5%60.3 mphCompare
255/50R1525.04"10.04"−0.6%59.6 mphCompare
165/80R1525.39"6.50"+0.8%60.5 mphCompare
195/65R1524.98"7.68"−0.9%59.5 mphCompare
265/50R1525.43"10.43"+0.9%60.6 mphCompare
205/65R1525.49"8.07"+1.2%60.7 mphCompare
245/55R1525.61"9.65"+1.6%61.0 mphCompare
225/60R1525.63"8.86"+1.7%61.0 mphCompare
165/75R1524.74"6.50"−1.8%58.9 mphCompare

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

SizeWheelDiameterDifference
225/35R1919"25.20"0.0%Compare
315/25R1919"25.20"0.0%Compare
195/60R1616"25.21"+0.1%Compare
265/25R2020"25.22"+0.1%Compare
235/50R1616"25.25"+0.2%Compare
265/30R1919"25.26"+0.2%Compare
205/45R1818"25.26"+0.3%Compare
295/35R1717"25.13"−0.3%Compare
195/80R1313"25.28"+0.3%Compare
205/75R1313"25.11"−0.4%Compare
295/40R1616"25.29"+0.4%Compare
235/60R1414"25.10"−0.4%Compare

One size up or down

Compare 185/70R15 with another size

With 195/70R15 tires, when your speedometer says 60 mph you are really going

61.3 mph

195/70R15 is +0.55 inches (+2.2%) in overall diameter. That is within the 3% most shops and makers allow.

185/70R15195/70R15Difference%
Overall diameter25.20"25.75"+0.55"+2.2%
Section width7.28"7.68"+0.39"+5.4%
Sidewall height5.10"5.37"+0.28"+5.4%
Circumference79.16"80.89"+1.73"+2.2%
Revolutions per mile800.4783.3−17.1−2.1%

Questions

How tall is a 185/70R15 tire?
A 185/70R15 tire is 25.2 inches tall (640 mm), calculated from the size. It is 7.3 inches wide with 5.1 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
What does 185/70R15 mean?
185/70R15 means a tire 185 mm wide, with sidewalls 70% as tall as the tire is wide (130 mm), radial construction (R), for a 15 inch wheel.
How many revolutions per mile does a 185/70R15 tire make?
About 800 revolutions per mile, based on a circumference of 79.2 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
What rim width fits a 185/70R15 tire?
Roughly 5.0" to 6.5". Check the tire maker's approved rim range for the exact model before buying wheels.
Can I use 235/55R15 instead of 185/70R15?
235/55R15 is −0.02 inches (−0.1%) 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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