2018 Buick Tire Fitment Guide

2018 Buick vehicles use six tire sizes across four models: 245/40R20 for Cascada and LaCrosse, 245/45R19 for LaCrosse, 235/50R18 for LaCrosse and Regal TourX, 225/55R17 for Regal Sportback, 245/45R18 for Regal Sportback, and 245/40R19 for Regal Sportback. Those sizes mount on 17-, 18-, 19-, and 20-inch wheels, so there is no single fitment that works across the full 2018 Buick range.

The practical takeaway is that you should identify the exact model and confirm the wheel diameter already on the car before comparing tire lines. Rim width recommendations also vary by size, with examples ranging from 6.0-8.0 inches on 225/55R17 up to 8.0-9.5 inches on some 245/40R19 and 245/40R20 products, so matching the tire to the actual wheel matters just as much as matching it to the model.

On a 2018 Buick, 245/40R20 is a metric radial tire size. The 245 is the section width in millimeters, the 40 is the aspect ratio, the R means radial construction, and the 20 is the wheel diameter in inches. Within the 2018 Buick range, that size is used on the Cascada and on certain LaCrosse applications.

That code tells you much more than width alone, because the shorter sidewall and 20-inch wheel requirement separate it from the 17-, 18-, and 19-inch Buick fitments. If your car currently wears 20-inch wheels, 245/40R20 keeps you in the correct diameter family; if it does not, moving to that size would require wheel changes and should not be treated as a simple alternate fitment.

No, 2018 Buick models do not all use the same tire size. Cascada uses 245/40R20, LaCrosse uses 235/50R18, 245/45R19, or 245/40R20 depending on wheel package, Regal Sportback uses 225/55R17, 245/45R18, or 245/40R19, and Regal TourX uses 235/50R18. Two sizes overlap between models, but several are model-specific.

That means year and make alone are not enough to choose correctly. A LaCrosse owner and a Regal TourX owner may both need 235/50R18, while a Regal Sportback owner could need a completely different 17-, 18-, or 19-inch setup. Checking the door placard, current tire sidewall, and wheel diameter before ordering is the simplest way to avoid chasing the wrong Buick fitment.

Most 2018 Buick fitments here are available as blackwall radials, which suits the late-model character of the Cascada, LaCrosse, Regal Sportback, and Regal TourX. A few visual alternatives do appear: 245/40R20 includes an RWL option, and 225/55R17 includes a BFGoodrich Silvertown Radial with a 1.50-inch wide whitewall. The rest of the 19-inch and 18-inch Buick sizes stay in blackwall form.

For a stock 2018 Buick look, blackwall is usually the natural choice. The whitewall 225/55R17 is more of a custom-style option than a factory-style appearance cue for a 2018 Regal Sportback, while the raised white letter 245/40R20 gives a sportier visual statement on Cascada or LaCrosse applications. Sidewall appearance does not change the basic fitment, but it can change the personality of the car dramatically.

BFGoodrich appears across every 2018 Buick size covered here, while Nitto also supports several of the 18-, 19-, and 20-inch fitments, and Pro-Trac appears in 245/40R20. The 245/40R20 size is available from BFGoodrich, Nitto, and Pro-Trac; 245/45R19 from BFGoodrich and Nitto; 235/50R18 from BFGoodrich and Nitto; 225/55R17 from BFGoodrich; 245/45R18 from BFGoodrich and Nitto; and 245/40R19 from BFGoodrich.

That brand mix gives 2018 Buick owners some room to choose a tire line that fits the car's role, whether that means a more performance-flavored option or a styling-driven sidewall choice. The easiest way to narrow it down is to start with your exact size, then compare the available series within that fitment rather than trying to compare unrelated Buick sizes against each other.

For 2018 Buick sizes where both appear, BFGoodrich g-Force Comp-2 A/S and BFGoodrich g-Force Phenom T/A share the same basic wheel diameter fitment but differ in speed rating and, in several sizes, load figures. In 245/40R20, for example, the Comp-2 A/S carries a W rating while the Phenom T/A carries a Y rating and reaches 1,709 pounds at 50 psi. Similar patterns appear in 245/45R19, 245/45R18, and 245/40R19, where the Phenom T/A versions carry Y ratings while the Comp-2 A/S versions remain W-rated.

That makes the comparison less about raw fitment and more about selecting the tire line whose specifications best match how you use your Buick. Both are radial blackwall choices within the same size families, so the right approach is to compare the exact size you need, then weigh speed rating, load figure, and any wheel-width recommendation differences before making a final selection.

Rim width recommendations vary by size on 2018 Buick vehicles. 225/55R17 products span 6.0-8.0 inches, with one whitewall version extending to 6.00-9.00 inches. 235/50R18 products use 6.5-8.5 inches. 245/45R18 and 245/45R19 products use 7.5-9.0 inches. 245/40R19 and 245/40R20 products use 8.0-9.5 inches.

Those ranges matter because a tire can share the correct nominal size yet still need a different wheel width window than another Buick fitment. Before ordering, measure or confirm the actual wheel on the car and compare it against the tire you want, especially if the car has aftermarket wheels or if you are switching between two tire lines that use the same size but carry slightly different approved rim-width wording.

The 2018 Buick sizes covered here are modern radial fitments, and none of the product size markings indicate tube-type construction. They are tubeless-style radial offerings across the 17-, 18-, 19-, and 20-inch sizes, which is consistent with the era and with the wheel types these Buicks commonly use.

Even with tubeless tires, the condition of the wheel, bead seat, and valve stem still matters. If a 2018 Buick has been sitting for long periods or has wheel damage or corrosion, have the wheel inspected during installation so the tire can seal correctly. That is especially worthwhile on larger-diameter low-profile fitments, where proper mounting and air retention are important to day-to-day drivability.

A 2018 Buick should be stored in a cool, dry, dark space away from direct sunlight, electric motors, battery chargers, welders, and other ozone sources that can age rubber. Keep the tires properly inflated, avoid long-term contact with standing moisture, and move the car periodically so the same section of tread is not carrying the load for months at a time.

That matters even more on lower-profile 17-, 18-, 19-, and 20-inch Buick fitments, because modern performance-oriented radials can develop temporary flat spotting if a car sits for extended periods. If the Buick will be parked for a season, using tire cradles or stands and checking pressures before it goes into storage can help preserve shape, ride quality, and sidewall condition.

On a 2018 Buick, tire age is usually more important than mileage once the car becomes a low-use second vehicle or collector-kept daily driver. A sound rule is to begin evaluating tires closely around five to seven years of age and to give serious replacement consideration as they approach ten years, regardless of remaining tread. The DOT date code on the sidewall is the best way to confirm age.

A Buick that covers only occasional weekend miles can still age out its tires before it wears them out. Heat cycles, sunlight, inflation history, and storage conditions all influence service life, so a tire that looks acceptable at a glance may still be too old for confident road use. Regular age checks are especially important on cars that sit more than they drive.

Tires on a 2018 Buick should be inspected before every drive and again before any longer trip. Look for pressure loss, sidewall cracking, cuts, bulges, irregular tread wear, and any signs that the tire has been run underinflated. Because these Buicks use modern radial sizes, also pay attention to impact damage from potholes or curb strikes, especially on the lower-profile 19- and 20-inch fitments.

A quick walk-around catches many problems before they turn into a roadside interruption. It is also smart to inspect the spare, check valve stems, and watch for steering vibration that may point to a damaged tire or wheel. On a car that sees mixed seasonal use, a spring inspection and a second one before fall driving are good habits in addition to pre-drive checks.

A 2018 Buick LaCrosse was originally a modern radial-tire car, and the size depended on its wheel package rather than on an old-style bias-ply convention. Within this model range, LaCrosse uses 235/50R18, 245/45R19, or 245/40R20. That means originality starts with confirming which wheel and size package belonged on your particular car before comparing individual replacement tires.

Because 2018 is a late-model application, authenticity is usually more about matching the correct modern size, sidewall appearance, and overall visual character than about chasing an antique-era construction detail. If you are restoring a LaCrosse to factory appearance standards, the safest path is to verify the original tire placard and wheel package, then use that as the benchmark for replacement fitment.

Yes, correct tire fitment still matters when showing a 2018 Buick, even though it comes from a much newer era than most concours subjects. Judges and knowledgeable enthusiasts notice whether the tire size suits the car's wheel package, whether the sidewall style looks appropriate, and whether the overall stance matches the Buick's intended presentation. A wide whitewall on a 2018 Regal Sportback, for instance, gives a very different impression than a blackwall performance radial.

For most 2018 Buicks, getting the right modern size and a visually appropriate sidewall matters more than pursuing a historic construction debate. If the car is being prepared for marque judging or preservation-class scrutiny, compare the car against original photos, window sticker information, and club guidance so the tire choice supports the exact appearance standard you are aiming for.

Where both appear in 2018 Buick fitments, BFGoodrich g-Force Sport Comp-2 and Nitto NT555 G2 overlap in basic size but differ in some supporting specifications. In 235/50R18, the BFGoodrich g-Force Sport Comp-2 carries a 97W rating and a 1,609-pound load figure, while the Nitto NT555 G2 is marked XL 101W and reaches 1,819 pounds at 50 psi. In 245/45R18, the BFGoodrich version carries a 96W rating with a 1,565-pound load figure, while the Nitto carries XL 100W and reaches 1,764 pounds at 50 psi.

That means the comparison should focus on the exact size your Buick needs, then on the specification details within that size rather than on brand name alone. Both are blackwall radials, but the load index and pressure relationship can differ. If your car regularly carries passengers, cargo, or extended highway use, it is worth comparing those figures carefully before settling on one tire series.

Yes, the 2018 Buick tire fitments covered here are modern radial designs suitable for highway use when they are the correct size, properly inflated, and in sound condition. The speed ratings in these sizes include W, which corresponds to 168 mph, and Y, which corresponds to 186+ mph. Those ratings are well beyond normal U.S. highway speeds, although they are not a substitute for proper maintenance or for the vehicle's own operating condition.

In real-world use, the bigger safety question is usually tire age, damage, inflation, or an incorrect replacement size rather than the raw speed rating itself. A 2018 Buick with healthy brakes, suspension, alignment, and fresh tires in the right size is generally better served by careful condition checks than by chasing a higher speed symbol that the car will never meaningfully approach on public roads.

Inflation pressure for a 2018 Buick should start with the factory placard or owner's manual for the exact model and wheel package, because the car's recommended running pressure is not the same thing as the tire's maximum pressure rating. Some tire specifications here include load-and-pressure figures such as 1,819 pounds at 50 psi for certain 235/50R18 and 225/55R17 products, 1,764 pounds at 50 psi for some 245/45R18 products, 1,653 pounds at 50 psi for some 245/40R19 products, and 1,874 pounds at 50 psi for some 245/45R19 products.

Those figures describe the tire's rated capability at a stated pressure, not the everyday setting you should automatically use on the car. The right approach is to follow Buick's recommended cold pressure for your exact model and wheel package, then adjust only when a tire manufacturer or vehicle placard calls for it. Never transfer a pressure assumption from one Buick size to another.

Before a longer drive in a 2018 Buick, inspect all four tires for cracking, cuts, bulges, punctures, uneven wear, and correct cold inflation pressure. Also check the spare, confirm the valve stems are sound, and make sure none of the wheels show visible damage from curb strikes or potholes. On larger 19- and 20-inch fitments, even small impacts can matter because the sidewall is shorter.

A longer-trip check should go beyond the tires and include the rest of the car's roadworthiness as well. Brakes, fluid levels, lights, battery condition, and alignment all influence how a Buick behaves at speed. If the car has been stored, driven infrequently, or recently purchased, a pre-trip inspection from a trusted shop is a sensible step before relying on it for sustained highway miles.