275/55R20 Tire Size
A 275/55R20 tire has a nominal calculated diameter of approximately 31.91 inches (810.5 mm), a nominal section width of about 10.83 inches (275 mm), and a sidewall height of about 5.95 inches (151.3 mm).
275/55R20 in Inches
When converted to US customary units, a nominal 275/55R20 tire measures approximately 31.91 inches in overall height with a section width of 10.83 inches mounted on a 20-inch wheel.
Note: The dimension 31.9" × 10.8" R20 is an approximate nominal descriptive conversion, not a physical flotation catalog tire designation.
275/55R20 Dimensions Table
The table below summarizes all derived nominal geometric parameters for the 275/55R20 size in both US customary and metric units.
| Measurement Parameter | Inches (US) | Millimeters (Metric) |
|---|---|---|
| Nominal Section Width | 10.83 in | 275 mm |
| Sidewall Height (55%) | 5.95 in | 151.3 mm |
| Wheel (Rim) Diameter | 20.00 in | 508.0 mm |
| Nominal Overall Diameter (Height) | 31.91 in | 810.5 mm |
| Nominal Radius | 15.95 in | 405.2 mm |
| Nominal Circumference | 100.25 in | 2546.3 mm |
| Theoretical Revolutions | 632 revs/mile | 393 revs/km |
What Does 275/55R20 Mean?
The markings on the sidewall of a 275/55R20 tire represent standard ISO metric dimensions:
The 275 indicates a nominal section width of 275 millimeters (approximately 10.83 inches).
The sidewall height is 55% of the nominal section width, measuring 151.3 mm (5.95 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 20 inches (508.0 mm).
275/55R20 Dimensional Context & Proportions
275/55R20 has a nominal calculated diameter of 31.91 inches, placing it about 0.09 inches below a nominal 32-inch diameter.
Its 55-series aspect ratio means the nominal sidewall height is 55% of the 275 mm section width, giving a calculated sidewall height of 151.3 mm (5.95 in).
The 275 in 275/55R20 represents a nominal section width of 275 mm, which converts to approximately 10.83 inches.
Compare 275/55R20 With Another Tire Size
Nearby 20-Inch Tire Sizes by Nominal Diameter
The table below lists alternative standard tire sizes mounted on 20-inch wheels that fall within a ±3.0% nominal diameter window relative to 275/55R20.
| Nearby Size | Diameter | Diameter Delta | Width Delta | Sidewall Delta |
|---|---|---|---|---|
| 275/55R20Current | 31.91" | Baseline (0.0%) | 10.83" | 5.95" |
| 255/55R20 | 31.04" | -0.87" (-2.7%) | -0.79" | -0.43" |
| 285/50R20 | 31.22" | -0.69" (-2.2%) | +0.39" | -0.34" |
| 305/50R20 | 32.01" | +0.10" (+0.3%) | +1.18" | +0.05" |
| 285/55R20 | 32.34" | +0.43" (+1.4%) | +0.39" | +0.22" |
| 265/60R20 | 32.52" | +0.61" (+1.9%) | -0.39" | +0.31" |
| 295/55R20 | 32.78" | +0.87" (+2.7%) | +0.79" | +0.43" |
±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 275/55R20 Tires
How tall is a 275/55R20 tire?
A nominal 275/55R20 tire has an overall calculated diameter (height) of 31.91 inches (810.5 mm). Physical mounted height can vary slightly between tire manufacturers, tread depths, and inflation pressures.
How wide is a 275/55R20 tire in inches?
A 275/55R20 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 275/55R20 considered a 32-inch tire?
In casual automotive reference sizing, a 275/55R20 tire (nominal diameter of 31.91 inches) is generally grouped within the "32-inch" nominal diameter category.
What is the sidewall height of a 275/55R20 tire?
The sidewall height of a 275/55R20 tire is 5.95 inches (151.3 mm). This is calculated by taking 55% of the 275 mm section width.
How many revolutions per mile does a 275/55R20 tire make?
A nominal 275/55R20 tire makes approximately 632 revolutions per mile (393 revolutions per kilometer).
Content is based on cited tire-industry standards, manufacturer documentation, and technical references where relevant.