245/55R18 Tire Size Guide

The 245/55R18 size code identifies a metric tire that is 245 millimeters wide, with a sidewall height equal to 55 percent of that width, built in radial construction, and made to fit an 18-inch wheel. In this case, that works out to an approximate sidewall height of 5.31 inches and an overall diameter of about 28.61 inches.

Modern metric sizing spells out width and profile much more directly than older numeric or alphanumeric systems. What it does not tell you by itself is everything about the tire's actual fitment on a vehicle, because wheel width, load requirements, fender clearance, and the tire's intended use still need to be checked before choosing a replacement.

The 245/55R18 fits an 18-inch wheel, which equals 457.2 millimeters at the bead seat. The wheel diameter must match exactly, because an 18-inch tire will not mount correctly on a wheel of any other diameter.

Wheel diameter is only one part of the fitment picture. Width and offset matter too, especially on modern cars with tight brake, strut, and fender clearances. Since this size appears with an 18-inch rim fitment, buyers should also confirm that the wheel itself is appropriate for the tire's profile and that the complete wheel-and-tire package clears the vehicle through full steering and suspension travel.

The 245/55R18 has a section width of 245 millimeters, which converts to about 9.65 inches. Section width measures the widest point of the inflated tire from sidewall to sidewall, not the width of the tread that actually contacts the road.

Clearance questions usually start with section width because that is the dimension most likely to crowd fender lips, inner wheelhouses, suspension parts, or brake hardware. Tread width is usually narrower, so using tread alone can be misleading. When comparing substitute sizes, start with section width and then look at overall diameter to understand both lateral and vertical clearance changes.

The 245/55R18 has an approximate overall diameter of 28.61 inches, or about 726.69 millimeters. That is the full height of the mounted and inflated tire measured from the ground to the top, straight through the center.

Overall diameter affects more than appearance. It influences ride height, wheel-opening fill, effective gearing, and speedometer readings, so it is one of the first dimensions to compare when replacing the size with another option. Even small changes can alter stance or clearance on vehicles with limited room around the tire at full turn or full suspension compression.

The 245/55R18 has an approximate sidewall height of 5.31 inches, which is about 134.87 millimeters. Sidewall height is measured from the wheel's bead seat to the outer edge of the tread on one side of the tire.

That measurement helps explain how the tire will look and behave. A sidewall in this range generally preserves more cushion than a lower-profile fitment while still working with a larger 18-inch wheel. Buyers comparing alternatives should remember that sidewall height contributes directly to overall diameter, so a change here can affect both ride character and wheel-opening appearance.

The 245/55R18 turns about 704.9 revolutions per mile. That figure comes from the tire's approximate circumference of 89.88 inches and helps show how often the tire rotates over a fixed distance.

Revolutions per mile matter when you compare this size with another one, because a meaningfully different number can change speedometer and odometer readings. A replacement tire that turns more times per mile is effectively smaller overall, while one that turns fewer times is taller. Buyers concerned with gearing feel, stance, or instrument accuracy should compare this value along with width and diameter.

No. Sharing an 18-inch wheel diameter does not make the 245/55R18 interchangeable with every other 18-inch size. Width, sidewall height, and overall diameter all change the way a tire fits within the wheel opening and around suspension, brake, and steering components.

Fitment decisions should start with the exact size requirement for the vehicle, then move to wheel width, offset, and physical clearance checks. A tire that is only slightly wider or taller on paper can still create rubbing or stance changes on a modern platform. When replacing this size, compare overall diameter and section width first, then confirm the wheel setup and the vehicle's load needs.

The 245/55R18 is primarily a regular-use street size for modern passenger-car applications, especially when a vehicle was originally set up around this diameter, width, and profile. Its proportions combine a substantial section width with a moderate sidewall, which is why it appears on performance-oriented and full-size passenger platforms.

Replacement suitability still depends on matching the vehicle's original specifications. Buyers should confirm the wheel diameter, compare overall tire height, and make sure the tire they choose meets the vehicle's load requirements. If the vehicle is being restored or modified, this size may favor modern drivability over strict historical appearance, so originality-minded builds should be reviewed more carefully.

The most important checks for the 245/55R18 are wheel diameter, wheel width, section width clearance, and overall tire height. An 18-inch tire must be used on an 18-inch wheel, and the tire's approximate 9.65-inch section width and 28.61-inch overall diameter should be compared against the available room around the car.

Clearance needs to be checked at the fender edge, inner liner, strut area, and steering range, especially on vehicles with aggressive offsets or lowered suspension. Load requirements matter just as much as physical fit. Before making a change, compare the current tire markings, review vehicle documentation, and inspect the actual wheel-and-tire package rather than assuming similar-looking sizes will behave the same way.

The 245/55R18 combines radial construction with a 55-series profile, so it generally offers a blend of controlled response and enough sidewall to avoid the harsh feel of very low-profile fitments. Its approximate 5.31-inch sidewall gives the tire some compliance while the 245-millimeter width supports a planted, modern road feel.

Actual steering behavior depends on more than size alone. Suspension condition, alignment, inflation, wheel width, and the specific tire design all influence how the vehicle responds. On a properly sorted car, this size usually feels more substantial than a narrower package, but buyers should still treat the tire's age and the wheel setup as major factors in ride and response.

The 245/55R18 is a modern radial size commonly used on passenger vehicles that see normal street and highway service. Its approximate 28.61-inch diameter and 704.9 revolutions per mile place it in a range that supports steady road use when the tire itself is in sound condition and correctly matched to the vehicle.

Highway behavior depends on the full system, not just the size code. Tire age, construction quality, balance, alignment, suspension wear, and load all influence stability and braking feel at speed. Before any long trip, inspect for cracking, bulges, uneven wear, and air loss, then verify that the chosen tire's current sidewall markings and load capability suit the vehicle's real operating demands.

Changing away from the 245/55R18 to a meaningfully taller or shorter tire can affect stance, speedometer readings, and the way the wheel opening looks. Because this size stands about 28.61 inches tall, even small diameter changes can become noticeable on vehicles with tight clearances or styling that depends on the tire filling the opening correctly.

A shorter substitute will usually increase revolutions per mile and can make the vehicle sit lower, while a taller one reduces revolutions per mile and may crowd the fender or suspension. Buyers considering a different size should compare section width and overall diameter together, since width changes influence lateral clearance while diameter changes affect ride height and gearing feel.

BFGoodrich is available in the 245/55R18 on this page. Even when only one brand appears in a size, buyers should still evaluate the tire by its construction type, intended use, sidewall treatment, and how closely its dimensions match the vehicle's requirements.

Brand choice matters, but so does selecting a tire that suits the build. A regularly driven street car may prioritize predictable radial road manners, while a visual or period-inspired build may care more about appearance details. The strongest approach is to choose a consistent set that matches the same use case at all four corners rather than mixing styles or priorities.

Quality in the 245/55R18 starts with correct sizing, sound radial construction, and consistency from tire to tire in the same set. Buyers should look for a tire that matches the vehicle's required dimensions, carries the needed load capability, and is appropriate for the way the car is actually driven rather than focusing on appearance alone.

Practical quality checks include even molding, clear sidewall markings, balanced dimensions, and a tire age that makes sense for road use. On modern passenger applications, drivability often matters as much as style, so it is worth comparing how the tire's section width, profile, and overall diameter align with the vehicle's suspension geometry and intended service.

The 245/55R18 can serve both purposes, but the priority should match the vehicle. Its radial construction favors modern road manners, while details such as a redline sidewall can make it attractive to buyers who want a more distinctive visual effect without leaving a modern metric size.

Enthusiasts working with a judged restoration should think more carefully about whether a modern radial format matches the car's original character. For a regularly driven vehicle, balanced dimensions and predictable behavior usually matter more than strict originality. Choosing one goal up front helps avoid compromises in stance, ride quality, and the overall look of the finished set.

The service life of the 245/55R18 depends on use, alignment, inflation habits, loading, road conditions, and tire age as much as tread depth. A regularly driven vehicle can wear this size unevenly if suspension parts are loose or alignment is off, even when the tire still looks acceptable at a glance.

Routine inspection is the best way to catch problems early. Check for cracking, cuts, bulges, irregular shoulder wear, and chronic air loss, and pay attention to any new vibration or pull. Even on a car that sees moderate mileage, age and heat exposure can shorten usable life, so replacement decisions should consider condition and time in service, not tread alone.

The 245/55R18 should be inspected regularly for uneven wear, punctures, sidewall damage, cracking, and air loss. Because it is a radial passenger-car size, owners should also pay attention to vibration, steering pull, or cupping wear, since those signs often point to alignment, balance, or suspension issues rather than a size problem by itself.

Good care starts with maintaining the vehicle properly and checking the tires before longer drives. Review inflation against the vehicle and tire markings, inspect tread and sidewalls when the tires are cold, and rotate or service the set as needed to keep wear even. A well-maintained chassis helps this size perform more consistently over time.

The 245/55R18 is normally a tubeless fitment. Even so, tube use is a wheel-and-tire-system question rather than a size question, so the final decision should be confirmed against the actual wheel and the specific tire being used.

Modern radial passenger sizes like this are commonly run without tubes when paired with the correct wheel, but wheel condition still matters. A damaged rim, an older specialty wheel, or a nonstandard setup can change what is appropriate. If there is any doubt, inspect the wheel carefully and confirm the correct practice with a qualified tire professional before installation.

The 245/55R18 should be replaced when it shows cracking, bulges, cuts, persistent air loss, severe uneven wear, or age-related deterioration, even if some tread remains. A tire can look usable from a distance and still be a poor candidate for continued road service if the structure or rubber condition has declined.

Replacement timing should be based on condition, age, and the way the vehicle is used, not on mileage alone. Cars driven at interstate speeds or under heavier loads leave less margin for a questionable tire. Before continuing to use any older set, inspect all four tires closely and compare the current sidewall markings and general condition with the vehicle's real demands.

The main safety checks for the 245/55R18 are tire condition, correct 18-inch wheel fit, adequate clearance, and matching the tire to the vehicle's load needs. Buyers and owners should inspect for visible damage, verify that the wheel diameter is correct, and confirm that the tire is not contacting suspension or bodywork anywhere in the steering or suspension range.

Long-trip preparation should also include checking for air loss, irregular wear, and any vibration that suggests balance or mechanical issues. On modern passenger cars, a tire that is technically the right size can still be a poor road choice if it is old, underinflated, or mounted on an unsuitable wheel. Careful inspection is more valuable than assumptions based on size alone.

Street-use requirements for the 245/55R18 depend on the specific tire, its current markings, and local regulations rather than the size code alone. The size itself does not guarantee that every tire built in 245/55R18 meets every rule in every state or use case.

Buyers should review the actual sidewall markings on the tire they plan to use and check local inspection or registration requirements where applicable. It is also smart to confirm that the tire's construction, condition, and load capability suit the vehicle's intended road use. A legal and practical decision comes from the complete tire-and-vehicle combination, not the size designation by itself.