A truck tire size chart helps you compare more than the number printed on the sidewall. It shows how a replacement or larger tire changes width, sidewall height, overall diameter, revolutions, and potential clearance. For a work truck, the chart must also be read alongside the tire’s load range, load index, inflation requirements, wheel limits, and the vehicle’s axle ratings. Start with the size on the driver-door placard and the owner’s manual, then use a chart to identify alternatives that stay close enough in diameter and preserve the load capacity your truck needs for towing, hauling, and everyday use.
Most modern trucks use a metric tire size such as LT275/65R18. Some off-road and flotation tires use an inch-based format such as 35x12.50R17. A truck tire size chart translates both formats into comparable dimensions, which is especially useful when moving between stock, all-terrain, mud-terrain, and towing-oriented tires.
| Marking | Example | What It Tells You | Why It Matters |
|---|---|---|---|
| Service description | LT | Light-truck tire designation | Often indicates a tire designed for higher-duty use; verify its exact load rating and pressure requirements. |
| Section width | 275 | Approximate tire width in millimeters | More width can affect wheel-well, suspension, and fender clearance. |
| Aspect ratio | 65 | Sidewall height as a percentage of width | A 65-series sidewall is 65% of 275 mm, before conversion to inches. |
| Construction | R | Radial construction | Nearly all current highway and truck tires are radial. |
| Wheel diameter | 18 | Required wheel bead-seat diameter in inches | The tire must match the wheel diameter exactly. |
| Load/speed service description | 123/120S | Single/dual load indexes and speed symbol, when shown | Must meet the vehicle’s requirements and intended use. |
For LT275/65R18, the tire is approximately 275 millimeters wide. Its sidewall is 65% of that width: 178.75 mm, or about 7.04 inches. Add two sidewalls to the 18-inch wheel diameter and the calculated overall diameter is about 32.1 inches. Actual mounted dimensions vary by tire model, approved rim width, tread depth, and manufacturing tolerances, so treat a calculator or chart as a comparison tool rather than a guarantee of physical clearance.
A flotation size states the approximate overall dimensions directly. In 35x12.50R17, “35” is the nominal overall diameter in inches, “12.50” is nominal section width in inches, “R” means radial, and “17” is the wheel diameter. The implied sidewall height is roughly 9 inches: subtract the 17-inch wheel from the 35-inch tire diameter, then divide the remaining 18 inches by two.
Flotation markings make diameter comparisons simple, but they do not replace the manufacturer’s specification sheet. Two tires both labeled 35x12.50R17 can differ in measured diameter, tread width, weight, approved wheel-width range, and load capability.
The following truck tire size chart uses calculated nominal dimensions. It is useful for understanding the direction and approximate scale of a change. It does not confirm that a size fits a specific Ford, Chevrolet, GMC, Ram, Toyota, Nissan, Jeep, or other truck configuration. Wheel offset, suspension height, brake clearance, trim level, steering travel, and factory options all affect fitment.
| Tire Size | Approx. Width | Approx. Sidewall | Approx. Diameter | Typical Comparison Use |
|---|---|---|---|---|
| 265/70R17 | 10.4 in | 7.3 in | 31.6 in | Common reference size for 17-inch truck wheels |
| 275/65R18 | 10.8 in | 7.0 in | 32.1 in | Moderate-width 18-inch option |
| 275/70R18 | 10.8 in | 7.6 in | 33.2 in | About one inch taller than 275/65R18 |
| 285/70R17 | 11.2 in | 7.9 in | 32.7 in | Common all-terrain upsizing reference |
| 285/75R16 | 11.2 in | 8.4 in | 32.8 in | Tall-sidewall 16-inch configuration |
| 35x12.50R17 | 12.5 in | 9.0 in | 35.0 in | Flotation-size off-road reference |
Diameter is often the first number people compare, but width deserves equal attention. A tire may be only slightly taller than stock yet substantially wider. That extra width can contact an upper control arm, sway-bar link, inner fender liner, mud flap, or bumper edge when the wheels are turned. A wheel with different offset can move the tire inward or outward enough to create rubbing even when the nominal tire size appears reasonable.
You can calculate a metric tire’s nominal diameter with a simple formula:
Overall diameter = wheel diameter + 2 × (section width × aspect ratio ÷ 25.4)
Use the aspect ratio as a decimal. For example, use 0.65 for a 65-series tire. The number 25.4 converts millimeters to inches.
To estimate speedometer effect, divide the new tire diameter by the original tire diameter. If the replacement is larger, the truck travels farther per wheel revolution. The speedometer and odometer may read lower than the truck’s actual road speed and distance until recalibrated. If the replacement is smaller, indicated speed may be higher than actual speed.
A truck tire size chart can identify physical dimensions, but it cannot tell you the safe load capacity unless you also read the full sidewall service description and the manufacturer’s load-and-inflation data. This distinction matters most for pickups that carry heavy cargo, pull trailers, use slide-in campers, or have aftermarket equipment that adds weight.
Load index is a code corresponding to a tire’s maximum load capacity at its specified maximum inflation pressure. An LT tire may display two load indexes, such as 123/120, because its allowed load differs when used as a single tire position versus a dual-wheel position.
Load range is a letter designation commonly found on LT tires, such as Load Range C, D, E, or F. It indicates a duty and inflation category, not a direct recommendation to inflate every tire to its maximum pressure. The tire maker’s published table connects load capacity to inflation pressure for that specific tire.
Ply rating is a historical strength category. It does not necessarily mean the tire physically contains that number of body plies. Avoid choosing a tire based on the ply-rating label alone.
A higher-load-range LT tire can make sense for a truck that regularly carries heavy loads or tows, provided the size, wheel, and inflation setup are appropriate. Its trade-offs may include more weight, firmer unloaded ride, and potentially different handling characteristics. A passenger-metric tire can be suitable for some light-duty trucks used mainly for commuting, but it should not replace an LT tire where the vehicle placard or intended service requires LT-rated capacity.
Moving to a taller or wider tire can improve ground clearance, fill the wheel wells, or support a desired off-road tread pattern. It can also create interference that does not appear while the truck is parked. A proper fitment check considers the tire’s full range of motion: steering left and right, suspension compression, body movement, and the additional width created by the selected wheel.
Lift kits and leveling kits may create more vertical room but do not automatically solve rubbing. A tire can still contact the frame, control arm, liner, or bumper because of width and wheel offset. Trimming components to force a fit should be approached carefully; it can affect parts intended to protect wiring, cooling components, or the body from debris.
| Option | Best For | Main Advantage | Primary Limitation | Verify Before Buying |
|---|---|---|---|---|
| Exact placard size | Daily driving, warranty-conscious owners, predictable towing use | Most straightforward fitment and calibration path | May not provide the look or extra clearance some owners want | Correct load rating, tire type, and matching axle set |
| Near-stock diameter alternative | Changing wheel diameter or seeking a different tread model | Can preserve gearing and speedometer behavior reasonably closely | Width and wheel offset may still cause clearance issues | Published dimensions, rim-width range, and steering clearance |
| Moderate upsizing | Owners seeking more ground clearance or a more aggressive stance | More tire sidewall or diameter may help on rough surfaces | Potential rubbing, added weight, altered gearing, and calibration needs | Full-compression clearance, wheel offset, load capacity, and recalibration |
| Large flotation-size change | Purpose-built off-road setups with planned supporting modifications | Substantial clearance and off-road tire availability | Can affect acceleration, braking feel, steering, fuel use, and component wear | Suspension, axle gearing, wheel fitment, braking, legal tire coverage, and professional inspection |
For most trucks used to tow or haul, staying with the original size or a close-diameter alternative is the lower-risk choice. It preserves the manufacturer’s intended gearing and reduces the chance that a tire change compromises clearance or capacity. A major upsize makes more sense when the entire vehicle setup has been evaluated, rather than when tire diameter is chosen only for appearance.
There is no universal size because clearance depends on the truck, factory wheel, wheel offset, tire model, suspension condition, and steering geometry. Some trucks accept a modest change while others rub with a similar-looking size. Check the exact tire manufacturer dimensions and inspect clearance at full lock and suspension compression rather than relying on a general claim.
No. A tire with greater load capacity does not increase the truck’s manufacturer-rated payload, GVWR, axle ratings, wheel ratings, or suspension capacity. It may provide an appropriate tire-capacity margin for the existing vehicle ratings, but it does not change those ratings.
Both tires have the same nominal width and fit an 18-inch wheel, but the 70-series tire has a taller sidewall. Calculated diameter changes from about 32.1 inches for 275/65R18 to about 33.2 inches for 275/70R18. That difference may affect clearance, speedometer accuracy, and gearing.
Mixing sizes on the same axle is generally not appropriate because it can affect handling, braking, and tire wear. Four-wheel-drive and all-wheel-drive systems can be especially sensitive to differences in tire circumference. Follow the vehicle manufacturer’s requirements for matching tires and seek professional guidance if a replacement cannot match the others.
LT tires may be appropriate if your truck’s placard specifies them or if the truck’s actual use requires their available load and inflation range. They can also bring ride and weight trade-offs when the truck is unloaded. Compare the exact tire’s load capacity at the pressure you will use, then make sure it meets the vehicle’s stated requirements.
A truck tire size chart is most useful when it helps narrow the choices before purchase. Match the replacement tire’s dimensions to your clearance limits, then confirm the exact model’s load capacity, approved wheel width, inflation data, and vehicle requirements. For a truck that tows, hauls, or runs on modified wheels and suspension, a qualified tire or alignment professional should inspect the intended setup before installation. That extra check is far less costly than discovering rubbing, incorrect calibration, or inadequate capacity after the tires are mounted.