A tire width chart is a quick way to compare the first number in common tire sizes, such as 205/55R16 or 245/45R18. That number represents the tire’s nominal section width in millimeters, not a guarantee of its exact mounted width. A wider replacement tire may improve dry-road steering response or give a different look, but it can also create rubbing, fit poorly on the wheel, change the overall diameter, or affect load capacity and wet-weather behavior. Start with the size on your vehicle’s tire placard and the sidewall of the current tire, then use a tire width chart to evaluate only alternatives that remain approved for your wheels and vehicle.
Most passenger vehicles in the United States use a metric tire-size format. Consider a tire marked 225/60R17 99H:
The width number is useful, but it does not describe the whole tire. A 225/60R17 and a 225/45R17 have the same nominal width, yet the 60-series tire has a much taller sidewall and a larger outside diameter. That difference can affect fender clearance, ride comfort, steering response, and speedometer accuracy.
Also distinguish section width from tread width. Section width is the sidewall-to-sidewall measurement used in the size designation. Tread width is the portion designed to contact the road and can differ substantially among tires carrying the same nominal size. Do not assume two 225 mm tires have identical tread footprints or clearance needs.
This tire width chart converts common nominal metric widths to approximate inches. It is best used as a comparison tool, not as a fitment approval chart. The actual width listed in a manufacturer’s specifications is the more useful number when clearance is tight.
| Nominal tire width | Approximate width in inches | Typical relative use | Fitment reminder |
|---|---|---|---|
| 155 mm | 6.1 in | Narrow compact-car fitments | Confirm load capacity before substituting a larger size. |
| 175 mm | 6.9 in | Small cars and some older passenger vehicles | Wheel width may limit safe alternatives. |
| 195 mm | 7.7 in | Compact cars and sedans | Check diameter if changing aspect ratio too. |
| 205 mm | 8.1 in | Many compact cars, sedans, and crossovers | Compare manufacturer-approved rim-width ranges. |
| 215 mm | 8.5 in | Passenger cars and smaller crossovers | Clearance can vary by tire design. |
| 225 mm | 8.9 in | Cars, crossovers, and light-duty vehicles | Do not overlook load index and tire diameter. |
| 235 mm | 9.3 in | Crossovers, performance cars, and pickups | Inspect steering and suspension clearance. |
| 245 mm | 9.6 in | Performance-oriented and larger-vehicle applications | A wider wheel may be required or preferred. |
| 255 mm | 10.0 in | Performance cars, SUVs, and trucks | Verify fender, liner, and suspension clearance. |
| 275 mm | 10.8 in | Wide performance and truck applications | Offset and wheel width become especially important. |
| 295 mm | 11.6 in | Specialty performance and heavy-duty applications | Use vehicle-specific fitment information. |
To convert a metric width yourself, divide millimeters by 25.4. For example, 225 mm divided by 25.4 equals about 8.9 inches. This conversion helps when comparing metric passenger tires with flotation-style light-truck sizes, but it does not make the two sizing systems directly interchangeable.
The number on the sidewall is nominal. Tire makers publish specification sheets that typically state a measured section width on a specified measuring rim. Mount that same tire on a narrower or wider approved wheel, and its section width can change.
For example, a tire mounted on the wider end of its approved rim-width range may spread outward and present a squarer sidewall profile. On a narrower wheel, the sidewalls may pull inward. Both installations may be within the tire maker’s approved range, but their clearance, steering feel, and wheel-rim protection can differ.
Design also matters. A tire with a pronounced rim protector, aggressive sidewall shape, or all-terrain construction may be wider in the area that matters for suspension or fender clearance than another tire in the same marked size. If a vehicle has limited room near a strut, control arm, brake hose, or inner fender liner, compare the manufacturer’s published section width and overall diameter for the exact tire model.
Changing only the width number is uncommon because the aspect ratio usually changes as well. The sidewall height is calculated from width and aspect ratio:
Sidewall height = tire width × aspect ratio
For a 225/60R17, the sidewall is approximately 135 mm tall: 225 × 0.60. A 235/55R17 is wider, but its sidewall is approximately 129 mm tall: 235 × 0.55. Its overall diameter may be relatively close to the original, which is why this type of size change is sometimes considered. “Close,” however, is not the same as compatible.
Overall diameter influences the distance traveled per tire revolution. A meaningful change can affect the speedometer and odometer readings, gearing feel, clearance, and the operation of vehicle systems that compare wheel speeds. On all-wheel-drive vehicles, keeping all four tires closely matched in size and circumference is particularly important. Follow the vehicle manufacturer’s guidance for replacement tires and mixing tires.
| Change under consideration | Possible benefit | Common limitation | What to verify |
|---|---|---|---|
| Same width, same complete size | Most straightforward replacement | Does not alter the vehicle’s appearance or response | Load index, speed rating, tire type, and placard requirements |
| One nominal width wider | May suit an approved wheel and desired handling balance | Can rub or change diameter if aspect ratio is not adjusted | Rim-width range, clearance at full steering lock, overall diameter |
| One nominal width narrower | May be useful for a wheel/tire package designed for winter conditions | May reduce wheel protection or fail load requirements | Approved fitment, load index, brake clearance, seasonal recommendations |
| Wider tire on the same wheel | May avoid buying new wheels | May exceed the wheel or tire maker’s approved range | Exact wheel width and the tire manufacturer’s rim-width specification |
| Wider tire and wider wheel | Can support a properly engineered performance setup | Offset and clearance issues become more likely | Wheel offset, bolt pattern, hub fit, fender and suspension clearance |
A tire width chart cannot tell you whether a tire fits your wheel. Wheel width is measured between the bead seats, not from outer lip to outer lip, and it is normally expressed in inches. Each tire size has a manufacturer-approved range of wheel widths.
Installing a tire outside that range can alter how the tread sits on the road and how the sidewall supports the vehicle. A tire that is too wide for the wheel may have a pinched profile and less predictable response. A tire that is too narrow for the wheel may stretch across the rim in a way the tire manufacturer did not approve, leaving sidewalls and beads outside their intended operating geometry.
Use the exact wheel width stamped on the wheel when available, or have a tire professional measure and identify it. Do not rely only on a wheel’s diameter. Two 17-inch wheels can have very different widths and offsets, so they may accept different tire sizes.
Wider tires are often associated with more grip, but the result depends on the tire compound, tread design, inflation pressure, vehicle weight, pavement temperature, and road surface. A high-quality tire in the original width can provide better real-world performance than a poorly suited wider tire.
A wider tire may support a broader tread design and can change steering response, particularly when paired with an appropriate wheel. It may also follow grooves or uneven pavement more noticeably, a behavior often called tramlining. The effect varies widely by vehicle and tire model.
Width alone does not determine wet grip or hydroplaning resistance. Tread depth, water-evacuation channels, compound, vehicle speed, and inflation pressure matter. For dedicated winter driving, a narrower approved tire can sometimes be selected as part of a manufacturer-supported winter package, but the correct choice depends on the vehicle, wheel, load requirements, and available tire sizes.
A width change often comes with a lower aspect ratio to hold overall diameter close to stock. That can mean a shorter sidewall, a firmer ride, and greater risk of wheel damage from potholes. Conversely, a wider tire with sufficient sidewall height may offer more rim protection, but only if it clears the vehicle and suits the wheel.
For most drivers replacing worn tires on an unmodified daily driver, choose the placard size or an equivalent size specifically approved for the vehicle and wheel. This approach preserves the manufacturer’s intended relationship among load capacity, clearance, speedometer calibration, stability systems, and ride quality.
A modest width change can make sense for an owner using a documented, vehicle-specific wheel and tire package. It may suit a performance-focused driver, a truck owner selecting an approved all-terrain setup, or someone building a seasonal wheel package. The main advantage is the ability to tailor the package to a use case. The limitation is that every related specification must be checked, rather than treating the tire width chart as a stand-alone answer.
Avoid changing width simply because a larger number appears more capable. Choose tires by their intended use, including all-season, summer, winter, touring, performance, or all-terrain needs, then select an approved size that meets your vehicle’s requirements.
Not necessarily. The 225 marking is the nominal section width, usually measured on a specified wheel width under standardized conditions. The actual width of the mounted tire can vary by brand, model, construction, and the wheel used.
Possibly, but only if the tire manufacturer lists your wheel width within the tire’s approved rim-width range and the tire clears the vehicle. You must also check overall diameter, load index, steering clearance, and any vehicle-specific requirements.
The nominal difference is 10 mm, or about 0.4 inch. The real difference may not be exactly 10 mm after mounting because tire models and wheel widths vary. The change in outside diameter depends on the aspect ratio, not width alone.
Width itself does not change speedometer readings. A change in the tire’s overall diameter does. If a wider tire also has a different sidewall height that changes the rolling circumference, the indicated speed and actual speed may no longer match as closely.
Not automatically. Wet and winter performance depend heavily on tread pattern, compound, tread depth, pressure, and conditions. Select a tire designed for the season and use an approved size rather than relying on width as the deciding factor.
Some all-wheel-drive vehicles can use approved alternate sizes, but all four tires generally need closely matched rolling circumference. Consult the owner’s manual and vehicle manufacturer guidance before changing sizes, especially if replacing fewer than four tires.
A tire width chart makes sidewall codes easier to compare: 235 is nominally wider than 225, and 225 is wider than 215. The safe replacement decision comes from the full size, approved wheel-width range, actual tire specifications, vehicle clearance, load requirements, and intended driving conditions. If you are unsure about an alternate size, bring the placard information, current tire size, and wheel details to a qualified tire professional before ordering tires.