275/70R18 tire size in inches and millimeters
275/70R18 measures 33.16 inches in overall diameter, 10.83 inches in section width, with a 7.58 inch sidewall.
Every dimension
| Size | In inches | In millimetres |
|---|---|---|
| Overall diameter | 33.16 in | 842.2 mm |
| Section width | 10.83 in | 275 mm |
| Sidewall height | 7.58 in | 192.5 mm |
| Circumference | 104.17 in | 2,645.8 mm |
| Revolutions per mile | 608.3 per mile | 378.0 per km |
Sizes that fit the same wheel
These sizes share a 18 inch wheel diameter and sit within 3% of 275/70R18 in overall diameter, which is the range a swap stays inside without recalibrating anything.
The percentage difference in overall diameter is the speedometer error: a tire 2% taller makes an indicated 60 mph a true 61.2 mph. They are the same number, so it is shown once.
| Alternate size | Overall diameter | Difference (in) | Difference (%) | Width difference (in) |
|---|---|---|---|---|
| 295/65R18 | 33.10 | -0.06 | -0.18 | 0.79 |
| 225/85R18 | 33.06 | -0.10 | -0.30 | -1.97 |
| 255/75R18 | 33.06 | -0.10 | -0.30 | -0.79 |
| 325/60R18 | 33.35 | 0.20 | 0.59 | 1.97 |
| 345/55R18 | 32.94 | -0.22 | -0.65 | 2.76 |
| 355/55R18 | 33.37 | 0.22 | 0.65 | 3.15 |
| 245/80R18 | 33.43 | 0.28 | 0.83 | -1.18 |
| 315/60R18 | 32.88 | -0.28 | -0.83 | 1.57 |
| 235/80R18 | 32.80 | -0.35 | -1.07 | -1.57 |
| 305/65R18 | 33.61 | 0.45 | 1.37 | 1.18 |
| 265/75R18 | 33.65 | 0.49 | 1.48 | -0.39 |
| 265/70R18 | 32.61 | -0.55 | -1.66 | -0.39 |
| 285/70R18 | 33.71 | 0.55 | 1.66 | 0.39 |
| 235/85R18 | 33.73 | 0.57 | 1.72 | -1.57 |
| 285/65R18 | 32.59 | -0.57 | -1.72 | 0.39 |
| 335/55R18 | 32.51 | -0.65 | -1.96 | 2.36 |
| 335/60R18 | 33.83 | 0.67 | 2.02 | 2.36 |
| 245/75R18 | 32.47 | -0.69 | -2.08 | -1.18 |
| 305/60R18 | 32.41 | -0.75 | -2.26 | 1.18 |
| 215/85R18 | 32.39 | -0.77 | -2.32 | -2.36 |
| 255/80R18 | 34.06 | 0.91 | 2.73 | -0.79 |
| 315/65R18 | 34.12 | 0.96 | 2.91 | 1.57 |
| 225/80R18 | 32.17 | -0.98 | -2.97 | -1.97 |
How this is worked out
sidewall height in millimetres = section width × aspect ratio ÷ 100
overall diameter in inches = wheel diameter + (section width × aspect ratio × 2) ÷ 2540
section width in inches = section width in millimetres ÷ 25.4
circumference in inches = π × overall diameter
revolutions per mile = 63360 ÷ circumference in inches
The divisor is 2540, not the 2550 some converters publish. Two sidewalls in inches are 2 × width × aspect ÷ (100 × 25.4), and the rounding costs about 0.07 inches at 34 inches.
For 275/70R18: the sidewall is 192.5 millimetres, two of them are 15.16 inches, and adding the 18 inch wheel gives 33.16 inches overall.
Questions
What size is 275/70R18 in inches?
33.16 inches in overall diameter, 10.83 inches in section width, with a 7.58 inch sidewall.
How tall is a 275/70R18 tire?
33.16 inches, which is 842.2 millimetres.
What do the numbers in 275/70R18 mean?
275 is the section width in millimetres, 70 is the sidewall height as a percentage of that width, and 18 is the wheel diameter in inches. Overall diameter is the wheel diameter plus two sidewalls: 33.16 inches.
Does 275/70R18 fit a 18-inch wheel?
Yes — the 18 in a metric tire size *is* the wheel diameter, so 275/70R18 is made for a 18 inch wheel. Rim width is a separate question the sidewall code does not answer.
What tire sizes are equivalent to 275/70R18?
295/65R18, 225/85R18, 255/75R18 are the closest by overall diameter, all on the same 18 inch wheel.
Fitting a size is not only a matter of diameter. Rim width, load rating, speed rating and clearance all decide whether a size works on a given vehicle, and none of them can be read off the sidewall code alone.