2018 Infiniti Tire Fitment Guide

2018 Infiniti vehicles use nine sizes across four model lines. The Q50 uses 225/55R17, 225/50R18, 245/40R19, and 265/35R19. The Q60 uses 255/40R19, 255/35R20, and 275/30R20. The Q70 and Q70L share 245/50R18 and 245/40R20. Rim diameter ranges from 17 to 20 inches, and rim-width guidance varies by size where it is available, including 6 to 8 inches for 225/50R18, 6 to 9 inches for some 225/55R17 applications, 8 to 9.5 inches for 245/40R19 and 245/40R20, 8.5 to 10 inches for 255/40R19 and 255/35R20, and 9 to 10.5 inches for 265/35R19.

The practical takeaway is that 2018 Infiniti fitment depends on the exact model and wheel package, not just the brand and year. A Q50 owner may be dealing with 17-, 18-, or 19-inch wheels, while a Q60 owner may be on either 19s or 20s, and the Q70 family follows a different sizing path altogether. Check the sidewall on the car now, then confirm wheel diameter before moving to brand or sidewall-style preferences.

On a 2018 Infiniti, 225/55R17 is a metric radial size. The 225 is the section width in millimeters, 55 is the aspect ratio, meaning the sidewall height is 55 percent of the section width, R means radial construction, and 17 is the wheel diameter in inches. In this year range, that size applies to the Q50. Products in 225/55R17 include Blackwall and Wide Whitewall versions, and some carry W speed ratings with a 112 mph ceiling.

That code matters because it tells you both the wheel diameter and the tire’s overall profile family. A 225/55R17 cannot be substituted casually with an 18- or 19-inch size from another 2018 Infiniti model, even if the vehicles look related. If your Q50 wears 17-inch wheels, start with 225/55R17 and then narrow the choice by visual style, intended driving use, and the specific tire series you prefer.

No, 2018 Infiniti models do not all use the same tire size. The Q50, Q60, and Q70 family each follow their own fitment pattern, and only the Q70 and Q70L share the same two sizes: 245/50R18 and 245/40R20. Every other size in the lineup is tied to a single model line. That means there is no universal 2018 Infiniti tire size that covers the full range.

This matters most when shopping by year and make alone, because the wrong tire can be very close in overall appearance while still requiring a different wheel diameter or width. A Q60 coupe tire package, for example, should not be treated as interchangeable with a Q50 sedan setup simply because both are sporty Infinitis from the same year. Identify the exact model first, then confirm the wheel size already on the car before comparing products.

2018 Infiniti tires are available in several sidewall treatments depending on size. Blackwall is the most common across the full range, especially in Q50 and Q60 performance sizes such as 245/40R19, 255/40R19, 255/35R20, and 275/30R20. The 225/55R17 Q50 size also appears in a Wide Whitewall version, while 245/40R20 for the Q70 and Q70L is available in both Blackwall and RWL form, and 245/50R18 for the Q70 and Q70L comes in RWL and Redline versions.

For a stock-looking 2018 Infiniti, Blackwall is the most natural visual fit because it matches the modern premium-sport character of the brand. Whitewall, redline, and raised white letter treatments make more sense for a custom build or a deliberate styling statement rather than a factory-style restoration. Once the correct size is settled, sidewall style becomes one of the clearest ways to tune the car’s appearance without changing wheel diameter.

Three brands cover 2018 Infiniti fitments here: BFGoodrich, Nitto, and Pro-Trac. BFGoodrich appears across most of the range, including Q50 sizes such as 245/40R19, 225/50R18, and 225/55R17, plus Q60 and Q70-family sizes like 255/40R19, 255/35R20, and 245/40R20. Nitto joins in several performance-oriented sizes including 265/35R19, 255/35R20, 275/30R20, and 245/40R20. Pro-Trac appears in 245/40R20 and 245/50R18, and also adds sidewall-style variety that the others do not.

Brand choice should follow fitment first and personality second. BFGoodrich gives the broadest coverage and several series choices in many sizes, Nitto fills selected modern performance sizes, and Pro-Trac is the route when an RWL or Redline look is part of the decision. If you are comparing tires for one exact size, look at speed rating, sidewall style, and rim-width compatibility before assuming every brand’s version serves the same role.

For 2018 Infiniti sizes where both appear, BFGoodrich g-Force and BFGoodrich g-Force Phenom T/A differ mainly in speed rating, load specification, and in some cases weight. In 245/40R19, g-Force choices appear with W ratings while the Phenom T/A carries a Y rating and a 1,653-pound load rating at 50 psi. In 255/40R19, g-Force versions include W and Y examples depending on series, while the Phenom T/A again carries a Y rating and a 1,764-pound load rating at 50 psi. Similar differences show up in 255/35R20 and 245/40R20.

That means the two series are not just different names on the same casing. If you are narrowing a tire for a specific 2018 Infiniti size, compare the exact speed symbol, any published load figure, and the approved rim-width range before treating one as interchangeable with another. Staying inside the vehicle’s proper size always comes first, but within that size, the series details help determine which version best matches your intended use.

Rim-width guidance for 2018 Infiniti tires varies by size. 225/50R18 fits 6 to 8 inches, while 225/55R17 appears in 6 to 8 inches on several products and up to 6 to 9 inches on the Silvertown Radial version. 245/40R19 and 245/40R20 use 8 to 9.5 inches. 255/40R19 and 255/35R20 use 8.5 to 10 inches. 265/35R19 uses 9 to 10.5 inches.

Those ranges are important because the correct tire size alone does not guarantee the tire suits every wheel built in that diameter. If your 2018 Infiniti already has aftermarket wheels, verify the wheel width before choosing a tire series, especially in the wider Q50 and Q60 applications. Staying within the approved width range helps preserve intended tread shape and keeps you from forcing a tire onto a wheel that is too narrow or too wide.

The 2018 Infiniti tires here are modern radial applications, and the size markings do not show tube-type designations such as TT. One 255/40R19 product explicitly carries a TL marking for tubeless use, while the rest follow the same general modern passenger-car pattern. Nothing in these sizes points toward an inner-tube requirement in normal use on appropriate modern wheels.

Even so, wheel condition still matters. If a 2018 Infiniti is using original-style modern wheels in good shape, tubeless fitment is the expected setup, but any wheel with damage, poor bead sealing, or a previous repair should be inspected before mounting new tires. Valve stems deserve the same attention, since a leaking stem can mimic a tire problem and is easy to overlook during a tire change.

A 2018 Infiniti should be stored away from direct sunlight, electric motors, welders, and other ozone sources that accelerate rubber aging. Keep the car in a dry, temperature-stable space, maintain proper inflation, and move it periodically so the tires do not sit in one contact patch for months at a time. Because every size here is radial, long static storage is generally less troublesome than with older bias-ply designs, but flat spotting and sidewall aging can still happen.

For seasonal or collector use, a short roll every few weeks helps, and some owners use tire cradles or stands if the car will sit for an extended period. Clean tires with mild soap and water rather than petroleum-based dressings. If the car is stored on the ground, make sure the surface stays dry and free of solvents, since both moisture and chemical exposure shorten tire life even when tread wear is minimal.

On a 2018 Infiniti, tire life should be judged by age as much as by tread depth. A useful rule is to begin evaluating tires closely around five to seven years from the DOT date code and to consider replacement as they approach ten years, even if the car is driven sparingly. That guidance matters especially on low-mileage luxury or collector-kept vehicles, where tread can look healthy while the rubber itself has aged.

Mileage alone can be misleading on a Q50, Q60, Q70, or Q70L that sees weekend or seasonal use. Check the DOT date code, inspect for cracking, hardening, and uneven wear, and pay attention to how the tire feels on the road compared with when it was newer. A lightly used tire can still be too old for confident road use, so age should be part of every replacement decision.

Tires on a 2018 Infiniti should be inspected before every drive and again before any longer trip. Look for sidewall cracking, cuts, bulges, punctures, uneven tread wear, and any sign that pressure is bleeding off between uses. A quick visual check takes only a moment and is especially worthwhile on cars that are driven irregularly, since small issues can develop unnoticed while the vehicle sits.

A more careful inspection every month is a good habit, including pressure checks when the tires are cold. If the car has been parked for weeks, pay extra attention to flat spotting, shoulder wear, and the condition of the spare if one is carried. Consistent inspection catches aging and setup issues early, which is more valuable on a modern luxury-performance car than waiting for tread wear alone to tell the story.

Yes, the radial tires used on 2018 Infiniti vehicles are highway-capable when they are the correct size, in sound condition, and inflated properly. Many of these sizes carry W or Y speed ratings, with W rated to 112 mph and Y rated to 186+ mph. Those ratings are well beyond normal U.S. highway speeds. In real use, tire age, condition, and inflation are usually more important than the headline speed symbol on a modern Infiniti sedan or coupe driven legally on public roads.

The important comparison is not just whether a tire can handle highway use, but whether it matches the exact wheel package on your Q50, Q60, Q70, or Q70L. A fresh, properly matched W-rated tire is far more reassuring than an aged Y-rated tire with cracking or pressure loss. Before sustained highway driving, confirm the size, inspect all four tires, and make sure the car’s suspension and alignment are not creating wear that compromises stability.

Inflation pressure for a 2018 Infiniti should follow the vehicle placard or owner’s manual for the exact model and wheel package, not a one-size-fits-all number borrowed from another Infiniti. Some tire products in these sizes publish maximum load and pressure figures such as 1,653 pounds at 50 psi for certain 245/40R19 and 265/35R19 versions, 1,709 pounds at 50 psi for some 225/50R18 and 245/40R20 versions, 1,764 pounds at 50 psi for some 255/40R19 versions, and 1,819 pounds at 50 psi for some 225/55R17 versions.

Those tire-side maximum figures are load-rating limits, not automatic running pressures for every 2018 Infiniti application. Use them only as part of understanding the tire’s capacity. For day-to-day inflation, the car’s factory recommendation is the better starting point because it accounts for weight distribution, ride, and handling. Recheck pressure when tires are cold, especially after weather swings or long storage periods.

Before a longer drive in a 2018 Infiniti, inspect each tire for cracking, cuts, bulges, punctures, and uneven wear, then verify cold inflation pressure. Also check the sidewalls for scuffing from curbs, confirm that the tread is wearing evenly across the width, and make sure the spare and inflator equipment are usable if the car carries them. On a modern performance-luxury car, a tire problem often shows up first as vibration, pull, or noise, so take those symptoms seriously.

Tires are only one part of the pre-trip picture, but they are the part in constant contact with the road. A longer run is also a good time to confirm alignment feels normal and that no wheel has a slow leak. If the car has been sitting, drive a short local loop first to feel for vibration or pressure loss before committing to a highway trip.