215/70R18 tire size in inches

A 215/70R18 tire measures

29.9" tall × 8.5" wide

5.93" sidewall on a 18" wheel. 676 revolutions per mile.

215/70R18 means a tire 215 mm wide, with sidewalls 70% as tall as the tire is wide (151 mm), radial construction (R), for a 18 inch wheel.

29.9"18" rim5.9"8.5" wide
215/70R18: 29.9 inches tall, 8.5 inches wide, on a 18 inch rim, drawn to scale

215/70R18 specs

Overall diameter (height)29.85 inches (758 mm)
Section width8.46 inches (215 mm)
Sidewall height5.93 inches (151 mm)
Wheel (rim) diameter18 inches
Circumference93.8 inches (2,382 mm)
Revolutions per mile676
Revolutions per kilometer420
Approximate rim width5.5" to 7.0"
In inches (flotation style)29.9x8.5R18
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 215/70R18 on a 18" wheel

These 18" sizes are within 3% of 215/70R18's overall diameter, the range most tire shops treat as interchangeable.

SizeDiameterWidthDifferenceReal speed at 60
335/45R1829.87"13.19"+0.1%60.0 mphCompare
275/55R1829.91"10.83"+0.2%60.1 mphCompare
305/50R1830.01"12.01"+0.5%60.3 mphCompare
235/65R1830.03"9.25"+0.6%60.4 mphCompare
255/60R1830.05"10.04"+0.7%60.4 mphCompare
295/50R1829.61"11.61"−0.8%59.5 mphCompare
205/75R1830.11"8.07"+0.9%60.5 mphCompare
245/60R1829.57"9.65"−0.9%59.4 mphCompare
195/75R1829.52"7.68"−1.1%59.3 mphCompare
225/65R1829.52"8.86"−1.1%59.3 mphCompare
325/45R1829.52"12.80"−1.1%59.3 mphCompare
265/55R1829.48"10.43"−1.3%59.2 mphCompare

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

SizeWheelDiameterDifference
285/35R2222"29.85"0.0%Compare
225/50R2121"29.86"0.0%Compare
345/40R1919"29.87"+0.1%Compare
275/50R1919"29.83"−0.1%Compare
235/75R1616"29.88"+0.1%Compare
295/25R2424"29.81"−0.1%Compare
305/45R1919"29.81"−0.1%Compare
235/80R1515"29.80"−0.2%Compare
335/30R2222"29.91"+0.2%Compare
355/35R2020"29.78"−0.2%Compare
315/40R2020"29.92"+0.2%Compare
295/55R1717"29.78"−0.3%Compare

One size up or down

Compare 215/70R18 with another size

With 225/70R18 tires, when your speedometer says 60 mph you are really going

61.1 mph

225/70R18 is +0.55 inches (+1.8%) in overall diameter. That is within the 3% most shops and makers allow.

215/70R18225/70R18Difference%
Overall diameter29.85"30.40"+0.55"+1.8%
Section width8.46"8.86"+0.39"+4.7%
Sidewall height5.93"6.20"+0.28"+4.7%
Circumference93.78"95.51"+1.73"+1.8%
Revolutions per mile675.6663.4−12.2−1.8%

Questions

How tall is a 215/70R18 tire?
A 215/70R18 tire is 29.9 inches tall (758 mm), calculated from the size. It is 8.5 inches wide with 5.9 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
What does 215/70R18 mean?
215/70R18 means a tire 215 mm wide, with sidewalls 70% as tall as the tire is wide (151 mm), radial construction (R), for a 18 inch wheel.
How many revolutions per mile does a 215/70R18 tire make?
About 676 revolutions per mile, based on a circumference of 93.8 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
What rim width fits a 215/70R18 tire?
Roughly 5.5" to 7.0". Check the tire maker's approved rim range for the exact model before buying wheels.
Can I use 335/45R18 instead of 215/70R18?
335/45R18 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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