A 275/70R18 tire size in inches works out to about 33.2 inches tall and 10.8 inches wide, with a 7.6-inch sidewall on an 18-inch wheel. Its theoretical circumference is about 104.2 inches, or roughly 608 revolutions per mile. Use these calculated dimensions to compare sizes, then check the exact tire model’s published specs and your vehicle’s fitment requirements before buying.
Quick Answer
A 275/70R18 tire calculates to about 33.2 inches tall, 10.8 inches in nominal section width, and 7.6 inches of sidewall. Its theoretical circumference is about 104.2 inches, or roughly 608 revolutions per mile. Actual published dimensions can vary by tire model, tread design, load range, and measuring rim width.
Key Takeaways
- A 275/70R18 tire has a calculated overall diameter of about 33.2 inches, or about 842 mm.
- The “275” means the tire has a nominal section width of 275 mm, or about 10.8 inches.
- The “70” means the sidewall height is 70% of the section width, which equals about 7.6 inches.
- The “R” means radial construction, and the “18” means the tire fits an 18-inch wheel only.
- A 275/70R18 is close to a 33-inch tire, but actual tire specs can differ by model and tread depth.
- Before switching from a smaller stock tire, check clearance, load capacity, speed rating, approved wheel width, correct cold inflation pressure, TPMS behavior, and speedometer error.
At a Glance
| Overall Diameter | About 33.2 in / 842 mm calculated |
| Section Width | 275 mm / about 10.8 in nominal |
| Sidewall Height | 192.5 mm / about 7.6 in |
| Circumference | About 104.2 in / 2,646 mm calculated |
| Revolutions per Mile | About 608 theoretical |
| Wheel Diameter | 18 in; approved wheel width depends on the exact tire model |
How Tall Is a 275/70R18 Tire?
A 275/70R18 tire is about 33.2 inches tall when you calculate the size from the tire code. In metric terms, that equals about 842 mm in theoretical overall diameter.
The word theoretical matters. Tire-size math gives you a reliable starting point, but published dimensions can vary by tire design, tread depth, load range, and measuring rim. Tire Rack notes that listed light-truck diameters are typical because tread designs and molded tread depths can change overall diameter. As a manufacturer-spec cross-check, Nitto lists the Ridge Grappler LT275/70R18 at 33.19 inches in overall diameter and the Exo Grappler LT275/70R18 at 33.43 inches. That is why the exact tire model’s spec sheet matters for clearance.
What Does 275/70R18 Mean?
The tire code tells you the tire’s nominal width, sidewall ratio, construction type, and wheel diameter. Michelin’s tire-marking guide explains that tire sidewall numbers identify key details such as width, aspect ratio, construction, wheel diameter, load rating, and speed rating.
- 275: The nominal section width in millimeters. In inches, 275 mm equals about 10.8 inches.
- 70: The aspect ratio. The sidewall height is 70% of the section width.
- R: Radial construction, which is the common construction type for modern passenger, SUV, and light-truck tires.
- 18: The wheel diameter in inches. A 275/70R18 tire fits an 18-inch wheel only.
Note: The size code does not tell you every fitment detail. You still need the tire maker’s published spec sheet for approved rim-width range, measured diameter, tread width, load capacity, and maximum inflation pressure. The maximum pressure molded on a tire is not automatically the correct everyday cold pressure for your vehicle.
How to Calculate 275/70R18 Tire Size
You can calculate the main 275/70R18 tire dimensions with simple tire-size math:
- Section width: 275 mm ÷ 25.4 = 10.8 inches
- Sidewall height: 275 mm × 0.70 = 192.5 mm, or 7.6 inches
- Overall diameter: 18 inches + 7.6 inches + 7.6 inches = about 33.2 inches
- Circumference: 33.2 inches × 3.1416 = about 104.2 inches
- Revolutions per mile: 63,360 inches ÷ 104.2 inches = about 608
The formula works because the tire has one sidewall above the wheel and one sidewall below it. You add both sidewalls to the 18-inch wheel diameter to estimate total unloaded tire height.
The calculated diameter is about 33.2 inches. Real published examples span at least 33.19 to 33.43 inches among current Nitto LT275/70R18 models, so use the exact tire model’s specification for final clearance checks.
What Are the 275/70R18 Dimensions?
The main 275/70R18 dimensions are a 33.2-inch calculated overall diameter, 10.8-inch nominal section width, 7.6-inch sidewall height, and 18-inch wheel diameter. Use these numbers as a planning tool, not as a final fitment guarantee.
| Measurement | 275/70R18 Value | What It Means |
|---|---|---|
| Section width | 275 mm / 10.8 in | Nominal sidewall-to-sidewall width |
| Sidewall height | 192.5 mm / 7.6 in | 70% of the section width |
| Wheel diameter | 18 in / 457.2 mm | Fits an 18-inch wheel only |
| Overall diameter | 842 mm / 33.2 in | Calculated unloaded tire height |
| Circumference | 2,646 mm / 104.2 in | Theoretical distance traveled per tire revolution |
| Revolutions per mile | About 608 | Theoretical rotations over one mile |
The diameter affects ride height and gearing. The section width affects clearance near suspension parts and fenders. The sidewall height affects ride feel, impact absorption, and how much room the tire needs under load.
How Wide Is a 275/70R18 Tire?
A 275/70R18 tire has a nominal section width of 275 millimeters, or about 10.8 inches. Section width is measured from sidewall to sidewall, not across the tread blocks. Bridgestone’s tire terminology guide defines section width as the sidewall-to-sidewall measurement, excluding raised lettering.
Section Width vs. Tread Width
The 275 mm number does not guarantee the exact tread width that touches the road. Actual tread width can change by tire model, highway versus all-terrain tread design, rim width, and inflation pressure.
Use section width when you compare tire sizes. Use the tire manufacturer’s spec sheet when you need exact tread width, approved rim-width range, load capacity, measured diameter, and mounted measurements.
Is a 275/70R18 the Same as a 33-Inch Tire?
A 275/70R18 is not exactly 33.0 inches tall, but it is close enough to be considered a 33-inch-class tire. Its calculated diameter is about 33.2 inches, so many drivers compare it with 33-inch tires when checking stance, clearance, and off-road fitment.
That small difference can still matter. A tire that is 33.2 inches tall may rub where a slightly shorter tire clears, especially at full steering lock, during suspension compression, or with heavy cargo.
Warning: Do not choose a tire size by height alone. Check your owner’s manual, tire placard, approved wheel width, load index, speed rating, fender clearance, suspension clearance, and brake clearance before changing sizes. NHTSA recommends using the original tire size or another size recommended by the vehicle manufacturer.
How Do 275/70R18 Tires Affect MPG and Speedometer?
A larger tire can affect both fuel economy and speedometer accuracy, but the exact change depends on what size you replace. A 275/70R18 has a larger rolling diameter than many stock truck and SUV tires, so it may make your speedometer read lower than your actual road speed.
Use this formula:
Actual speed = indicated speed × new tire diameter ÷ old tire diameter
For example, using theoretical dimensions, a 265/65R18 is about 31.6 inches tall and a 275/70R18 is about 33.2 inches tall. That is roughly a 5.1% diameter increase. If the vehicle were calibrated perfectly for the smaller size, an indicated 60 mph would correspond to about 63 mph after the change. For final recalibration, use the exact tire model’s published dimensions or revolutions-per-mile data when available.
Fuel economy can also change after a tire-size increase. Larger or more aggressive tires may weigh more, create more rolling resistance, and alter effective gearing. Still, no single MPG-loss number applies to every vehicle. Tire model, tread pattern, inflation pressure, load, alignment, driving speed, and terrain all matter.
Pro Tip: After changing tire size, compare GPS speed with your dashboard speedometer. If the difference is large, ask a qualified shop about recalibration options for your vehicle.
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How Does 275/70R18 Compare to 285/70R18 and 265/65R18?
Compared with a 285/70R18, the 275/70R18 is slightly narrower and shorter. Compared with a 265/65R18, the 275/70R18 is much taller and slightly wider. Tire Rack also notes that published dimensions can vary by specific tire design, so you should check the individual tire’s spec page before buying. Tire Rack’s light-truck tire-size comparison guide is useful for checking common size categories.
| Size | Width | Sidewall | Diameter | Revs/Mile | Difference vs 275/70R18 |
|---|---|---|---|---|---|
| 265/65R18 | 10.4 in | 6.8 in | 31.6 in | About 639 | About 1.6 in shorter and 0.4 in narrower |
| 275/70R18 | 10.8 in | 7.6 in | 33.2 in | About 608 | Baseline |
| 285/70R18 | 11.2 in | 7.9 in | 33.7 in | About 598 | About 0.6 in taller and 0.4 in wider |
The jump from 265/65R18 to 275/70R18 is significant because the tire gets about 1.6 inches taller. That raises the axle and underbody by about half the diameter increase, or roughly 0.8 inch. The jump from 275/70R18 to 285/70R18 is smaller, but it still adds width and height that may affect rubbing, steering clearance, and suspension travel.
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Will 275/70R18 Tires Fit My Vehicle?
A 275/70R18 tire may fit many trucks and SUVs, but fitment depends on the exact vehicle, trim, wheel offset, suspension height, and tire model. You should not assume it fits just because another owner runs the same size.
Before buying, check these points:
- Factory tire size: Compare the new diameter with the size on your tire placard or owner’s manual.
- Load index or load range: Match or exceed the vehicle manufacturer’s required load capacity.
- Speed rating: Use a rating that meets your vehicle’s requirements.
- Wheel width: Confirm your wheel falls within the tire manufacturer’s approved rim-width range.
- Clearance: Check the fender liner, upper control arm, sway bar, mud flaps, and bumper area.
- Full-lock turning: Test left and right steering clearance after installation.
- Suspension compression: Leave room for bumps, cargo, towing tongue weight, and off-road articulation.
- Pressure, TPMS, and speedometer: Do not use the tire sidewall’s maximum pressure as your target. For the original tire size, follow the vehicle placard. For an alternate size, have the correct load-supporting cold pressure confirmed for the vehicle and tire, then verify TPMS operation and speedometer accuracy.
NHTSA’s tire safety guide recommends buying the same tire size listed in the owner’s manual or Tire and Loading Information Label unless the vehicle manufacturer recommends another size. NHTSA also says the recommended cold pressure comes from the vehicle manufacturer’s label or owner’s manual, not from the maximum pressure molded on the tire. If you have any doubt about an alternate size, ask a qualified tire dealer or installer to confirm size, load capacity, pressure, and clearance for your vehicle.
If you are checking this size for a Tundra, see our vehicle-specific guide to whether 33-inch tires fit a stock Toyota Tundra rather than treating a generic 275/70R18 calculation as a fitment guarantee.
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275/70R18 Tire Size: Bottom Line
A 275/70R18 is a 33-inch-class tire that calculates to about 33.2 inches tall, 10.8 inches in nominal section width, and 7.6 inches of sidewall. Use those numbers for size comparison and speedometer estimates. Before buying, confirm the exact tire model’s published diameter, approved wheel-width range, load and speed ratings, vehicle clearance, and the correct cold inflation pressure for your setup.
Frequently Asked Questions
How tall is a 275/70R18 tire in inches?
A 275/70R18 tire is about 33.2 inches tall based on the standard tire-size calculation. Real tire specs can vary slightly by manufacturer, tread design, load range, air pressure, and wheel width.
Is a 275/70R18 the same as a 33-inch tire?
It is very close. A 275/70R18 calculates to about 33.2 inches tall, so it fits the 33-inch tire class. It is not exactly 33.0 inches, and actual tire measurements can vary by model.
Is a 275/70R18 a 35-inch tire?
No. A 275/70R18 calculates to about 33.2 inches tall, which is roughly 1.8 inches below a nominal 35-inch size. Actual tires labeled as 35-inch sizes can also vary by model, so compare published specifications rather than the size name alone.
Is a 275 tire equal to a 33-inch tire?
Not always. The number 275 only tells you the nominal section width in millimeters. You also need the aspect ratio and wheel diameter. A 275/70R18 is about 33.2 inches tall, but other 275-size tires can be shorter or taller.
What does the R mean in 275/70R18?
The R means radial construction. In this size, 275 is the nominal width in millimeters, 70 is the aspect ratio, R is the construction type, and 18 is the wheel diameter in inches.
What rim does a 275/70R18 tire fit?
A 275/70R18 tire fits an 18-inch wheel diameter. The correct wheel width is not determined by the “18” alone; use the exact tire model’s approved rim-width range from the manufacturer before mounting it.
