Tire Size Conversion
275/70r18 to inches
275/70R18 has a nominal width of 275 mm and an estimated outside diameter of 33.16 inches. Actual tire dimensions vary by manufacturer and operating conditions.
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NIST describes the standard inch as exactly equivalent to 25.4 mm
. NIST length definition. Michelin — reading tire markings. Method and limitations.
Nominal tire-size calculations for 275/70r18: section width, estimated sidewall height, outside diameter, circumference, and revolutions per mile. Actual dimensions vary by tire, rim, pressure, load, and wear.
Section width
275 mm
10.83 inches
Sidewall height
192.5 mm
7.58" (70% of width)
Wheel (rim) diameter
18"
457.2 mm
Overall diameter
33.16"
842.2 mm
Estimated circumference
104.17"
2645.8 mm
Estimated revolutions per mile/km
608 revs/mile
378 revs/km
About 275/70r18 tire size
The size 275/70r18 indicates a section width of 275 mm (10.83 inches), an aspect ratio of 70% (sidewall height 192.5 mm or 7.58 inches), and a 18-inch wheel. Estimated outside diameter calculates to 33.16 inches (842.2 mm), with an estimated geometric circumference of 104.17 inches.
Use these measurements to estimate speedometer error and clearance changes when switching sizes. For multi-size comparison and speed error calculation, try our dedicated tire size calculator.
Common tire sizes
Compare the nominal dimensions of 275/70r18 with other tire sizes. Confirm vehicle approval, rim compatibility, clearances, and load and speed ratings separately.
Sources and calculation notes
275/70R18 has a nominal width of 275 mm and an estimated outside diameter of 33.16 inches. Actual tire dimensions vary by manufacturer and operating conditions.
Method: Sidewall height in mm = width × aspect ratio / 100. Estimated diameter in mm = rim inches × 25.4 + 2 × sidewall height; circumference = π × diameter.
Scope: Actual inflated size and rolling circumference vary by product, load, pressure and wear. Fitment also requires clearance, rim width, load and speed checks.
Content maintained by mmtoinches.im. Updated and reference notes reviewed . How we calculate and present measurements. Sources support the stated definitions; examples and calculators are not certification of a product or compliance with a standard.