275/65R18 Tire Size
A 275/65R18 tire has a nominal calculated diameter of approximately 32.07 inches (814.7 mm), a nominal section width of about 10.83 inches (275 mm), and a sidewall height of about 7.04 inches (178.8 mm).
275/65R18 in Inches
When converted to US customary units, a nominal 275/65R18 tire measures approximately 32.07 inches in overall height with a section width of 10.83 inches mounted on a 18-inch wheel.
Note: The dimension 32.1" × 10.8" R18 is an approximate nominal descriptive conversion, not a physical flotation catalog tire designation.
275/65R18 Dimensions Table
The table below summarizes all derived nominal geometric parameters for the 275/65R18 size in both US customary and metric units.
| Measurement Parameter | Inches (US) | Millimeters (Metric) |
|---|---|---|
| Nominal Section Width | 10.83 in | 275 mm |
| Sidewall Height (65%) | 7.04 in | 178.8 mm |
| Wheel (Rim) Diameter | 18.00 in | 457.2 mm |
| Nominal Overall Diameter (Height) | 32.07 in | 814.7 mm |
| Nominal Radius | 16.04 in | 407.3 mm |
| Nominal Circumference | 100.77 in | 2559.5 mm |
| Theoretical Revolutions | 629 revs/mile | 391 revs/km |
What Does 275/65R18 Mean?
The markings on the sidewall of a 275/65R18 tire represent standard ISO metric dimensions:
The 275 indicates a nominal section width of 275 millimeters (approximately 10.83 inches).
The sidewall height is 65% of the nominal section width, measuring 178.8 mm (7.04 inches).
R indicates radial construction, where the main carcass cords run approximately radially from bead to bead.
Designed to fit a wheel (rim) with a diameter of 18 inches (457.2 mm).
275/65R18 Dimensional Context & Proportions
275/65R18 has a nominal calculated diameter of 32.07 inches, placing it about 0.07 inches above a nominal 32-inch diameter.
Its 65-series aspect ratio means the nominal sidewall height is 65% of the 275 mm section width, giving a calculated sidewall height of 178.8 mm (7.04 in).
The 275 in 275/65R18 represents a nominal section width of 275 mm, which converts to approximately 10.83 inches.
Compare 275/65R18 With Another Tire Size
Nearby 18-Inch Tire Sizes by Nominal Diameter
The table below lists alternative standard tire sizes mounted on 18-inch wheels that fall within a ±3.0% nominal diameter window relative to 275/65R18.
| Nearby Size | Diameter | Diameter Delta | Width Delta | Sidewall Delta |
|---|---|---|---|---|
| 275/65R18Current | 32.07" | Baseline (0.0%) | 10.83" | 7.04" |
| 285/60R18 | 31.46" | -0.61" (-1.9%) | +0.39" | -0.31" |
| 265/65R18 | 31.56" | -0.51" (-1.6%) | -0.39" | -0.26" |
| 255/70R18 | 32.06" | -0.02" (-0.1%) | -0.79" | -0.01" |
| 285/65R18 | 32.59" | +0.51" (+1.6%) | +0.39" | +0.26" |
| 265/70R18 | 32.61" | +0.53" (+1.7%) | -0.39" | +0.27" |
±3.0% is used only as a configurable discovery window for identifying dimensionally nearby sizes. It is not a safety limit, compatibility threshold, replacement recommendation, or vehicle-fitment approval.
Nominal vs Actual Tire Dimensions
The dimensions listed on this reference page are nominal calculated figures derived from standard tire-size geometry. Tire-industry standards and manufacturer specifications are referenced where relevant.
Actual mounted dimensions can vary by tire manufacturer and model, tread design, measuring rim width, production tolerances, tread wear, and test or operating conditions. Consult the tire manufacturer’s published specifications when measured dimensions are required.
Technical Boundaries & Fitment Verification
Changing tire specifications may require separate load-capacity and cold inflation pressure verification. Dimensional size alone does not determine vehicle load class, speed rating, or approved wheel-width ranges.
Frequently Asked Questions About 275/65R18 Tires
How tall is a 275/65R18 tire?
A nominal 275/65R18 tire has an overall calculated diameter (height) of 32.07 inches (814.7 mm). Physical mounted height can vary slightly between tire manufacturers, tread depths, and inflation pressures.
How wide is a 275/65R18 tire in inches?
A 275/65R18 tire has a nominal section width of 275 mm, which converts to approximately 10.83 inches. Actual mounted cross-section width can vary depending on wheel rim width, tire model, and manufacturing tolerances.
Is 275/65R18 considered a 32-inch tire?
In casual automotive reference sizing, a 275/65R18 tire (nominal diameter of 32.07 inches) is generally grouped within the "32-inch" nominal diameter category.
What is the sidewall height of a 275/65R18 tire?
The sidewall height of a 275/65R18 tire is 7.04 inches (178.8 mm). This is calculated by taking 65% of the 275 mm section width.
How many revolutions per mile does a 275/65R18 tire make?
A nominal 275/65R18 tire makes approximately 629 revolutions per mile (391 revolutions per kilometer).
Content is based on cited tire-industry standards, manufacturer documentation, and technical references where relevant.