The 2018 Audi S4 sits in the modern sport-sedan sweet spot, blending Audi’s understated design language with the kind of all-weather performance and everyday refinement that made the S4 such a strong enthusiast choice. For this exact model year, tire selection starts with two primary radial fitments: 245/40R18 and 245/35R19. Both are modern metric radial sizes, so the key decision is confirming which wheel diameter is on the car before comparing tire options. From there, the choice shifts to brand, tire series, and sidewall presentation, especially for 18-inch applications with more visual variety. That matters whether the goal is stock-style road use, a more distinctive appearance, or simply matching the current wheel setup correctly.
Which Tire Size Is Right for The 2018 Audi S4
The 2018 Audi S4 uses two primary tire sizes, and both are radial fitments. The first step is confirming whether the car is on 18-inch or 19-inch wheels, since that determines whether 245/40R18 or 245/35R19 applies. Premium Plus and Prestige models can use either size, so wheel diameter matters more than trim level when choosing the correct tire.
A 245/35R19 tire uses a 245-millimeter section width, a 35-series aspect ratio, radial construction, and a 19-inch rim diameter. On the 2018 Audi S4, this is a modern low-profile fitment that suits cars equipped with 19-inch wheels and keeps selection focused on contemporary performance-oriented radial designs. Available choices include BFGoodrich and Nitto, with blackwall styling across series such as g-Force Comp 2 AS, g-Force Phenom T/A, and NT555 G2. This size is the right place to start when the car already has 19-inch wheels and the goal is to stay with the proper rim diameter while comparing brand and series character.
A 245/40R18 tire carries the same 245-millimeter nominal width as the 19-inch option, but its 40-series profile is paired with an 18-inch wheel. For the 2018 Audi S4, this radial size opens up the broadest range of product choices, including BFGoodrich, Nitto, M&H Racemaster, and Pro-Trac offerings. Blackwall, Redline, and RWL sidewall treatments are available here, along with tire series such as g-Force Comp 2 AS, g-Force Sport Comp 2, Street Pro III, NT555 G2, and Drag Radial. This size deserves a closer look when the car is on 18-inch wheels and appearance or intended use is part of the buying decision.
Tire fitment is straightforward across the covered 2018 Audi S4 sub-models because Premium Plus and Prestige both use the same two primary sizes. The important check is not trim level, but whether the car is on 18-inch or 19-inch wheels before choosing a tire.
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2018 Audi S4 Premium Plus
The 2018 Audi S4 Premium Plus can use either of the two primary radial tire sizes for this model year. Tire selection comes down to confirming the wheel diameter on the car, then comparing the available brands, series, and sidewall treatments within that correct size.
The 2018 Audi S4 Prestige follows the same fitment pattern, with both primary radial sizes applicable depending on wheel setup. That makes wheel confirmation the first step, followed by choosing the tire that best matches the car’s appearance goals and intended driving use.
The tire sizes listed on this page assume factory-standard vehicle configuration. The following modifications may affect tire fitment and are not reflected in this guide:
Suspension changes (lowering, lift kits, spring replacements)
Body alterations (fender modifications, custom bodywork)
If your vehicle has been modified from factory specifications, verify tire clearance before purchase.
Best 2018 Audi S4 Tires for Sale
Available 2018 Audi S4 tire choices span 245/35R19 and 245/40R18 radial fitments from BFGoodrich, Nitto, M&H Racemaster, and Pro-Trac. Buyers can compare tire series, blackwall versus redline or raised white letter styling on 18-inch applications, and rim-width specifications where they are provided.
These FAQs focus on the two tire sizes used on the 2018 Audi S4, wheel-diameter confirmation, radial tire selection, sidewall and brand differences, and the fitment checks worth making before regular road use.
Tire Size & Fitment
What tire size fits a 2018 Audi S4?
The 2018 Audi S4 uses two primary tire sizes: 245/40R18 and 245/35R19. Both are radial sizes, and both appear across the covered S4 trim levels, so the car does not rely on one size exclusively by model name alone.
The practical next step is checking which wheels are actually on the car. An S4 with 18-inch wheels needs the 245/40R18 size, while a car on 19-inch wheels needs 245/35R19. That check matters even more on used cars, since wheel packages can change over time without any visible trim-level clue.
What size rim does a 2018 Audi S4 use?
The 2018 Audi S4 uses either an 18-inch or 19-inch rim, depending on which of its two primary tire sizes is on the car. The 245/40R18 size matches an 18-inch wheel, and the 245/35R19 size matches a 19-inch wheel.
Rim diameter should be confirmed before anything else because it determines the tire size category immediately. Looking at the current sidewall is usually the fastest check, but it is also worth confirming the wheels themselves if the car has been modified or fitted with a different package after it left the original owner.
Do all 2018 Audi S4 sub-models use the same tire size?
Premium Plus and Prestige versions of the 2018 Audi S4 share the same two tire-size possibilities: 245/40R18 and 245/35R19. In other words, trim level does not create a separate tire-size pattern here the way it can on some other vehicles.
That means tire choice depends more on the wheel setup than on the badge on the trunk. A buyer should verify the actual wheel diameter, then compare available tires in that exact size. This avoids ordering around trim assumptions when the car may already be running a different factory-style or aftermarket wheel package.
Choosing the Right Tire
What should I consider when choosing a tire for a 2018 Audi S4?
Start with the correct size for the wheel on the car, since the 2018 Audi S4 uses either 245/40R18 or 245/35R19. From there, compare radial tire series, rim-width compatibility where it is stated, sidewall appearance, load figures when shown, and the kind of driving the car is expected to see.
That approach keeps the decision grounded in fitment first and preference second. Some owners will focus on a clean blackwall performance look, while others may want the visual character of a redline or raised white letter 18-inch tire. Matching the tire to both the wheel and the car’s use is more useful than chasing one specification by itself.
What sidewall styles are available for 2018 Audi S4 tires?
Sidewall style depends on the tire size you are shopping. The 245/35R19 choices are blackwall, while the 245/40R18 size includes blackwall options as well as redline and RWL, which is a raised white letter presentation.
That difference can shape the buying decision if appearance matters as much as fitment. A blackwall keeps a modern, understated look, while redline and raised white letter tires create a more deliberate visual statement. The key is to make that choice only after confirming the car is on the 18-inch wheel setup that supports those sidewall variations.
What brands offer tires for the 2018 Audi S4?
Tires for the 2018 Audi S4 are available from BFGoodrich, Nitto, M&H Racemaster, and Pro-Trac across the two primary sizes. Brand availability varies by size, with 245/35R19 centered on BFGoodrich and Nitto, while 245/40R18 opens up the broadest range of brands and series.
Brand alone should not be the only filter. It is more useful to compare the correct size, the tire series within that brand, the sidewall treatment, and any stated rim-width or load information that applies to the way the car is set up. That gives a fuller picture than treating all tires from one brand as the same option.
Restoration & Appearance
Which tire should I choose for a period-style 2018 Audi S4?
A period-style approach on a 2018 Audi S4 usually means staying with the correct modern metric radial size for the wheel already on the car, then choosing a tire that suits the visual tone you want. That could mean a restrained blackwall look or, on 18-inch applications, a more noticeable redline or raised white letter presentation.
Because this is a recent performance sedan, appearance choices are less about antique-style authenticity and more about preserving a cohesive era-appropriate look. The smartest path is to confirm the current wheel diameter first, then decide whether the goal is a clean stock-leaning presentation or a more customized visual statement within the proper size.
How does tire construction affect the appearance of a restored 2018 Audi S4?
On the 2018 Audi S4, tire construction is straightforward because the primary fitments are radial. The appearance difference comes less from construction type and more from profile, wheel diameter, and sidewall treatment, especially when comparing the 18-inch and 19-inch setups.
That means the visual result is shaped by the complete wheel-and-tire combination rather than by a bias-ply-versus-radial decision. A lower-profile 19-inch blackwall setup presents differently than an 18-inch tire with a redline or raised white letter sidewall, so owners aiming for a tidy restoration-style finish should evaluate the whole package together.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 2018 Audi S4?
Yes. Modifications can affect tire fitment on a 2018 Audi S4 even when the tire size itself appears correct. Aftermarket wheels, suspension changes, ride-height adjustments, or body modifications can all change the space available around the tire and alter how well a given setup works in real driving conditions.
A car that still uses 245/40R18 or 245/35R19 may still need closer checking if the wheel width, offset, or suspension geometry has changed. It is smart to inspect steering clearance, inner-fender space, and the tire’s relationship to the suspension before assuming the current setup remains trouble-free under full turn or compression.
What should I inspect before driving a 2018 Audi S4 on new tires?
Before driving a 2018 Audi S4 on new tires, inspect the wheel diameter and condition, confirm the tire size matches the wheel, and check inflation, valve stems, and visible clearances. It is also worth looking over the suspension and alignment-related wear points if the previous tires showed uneven tread patterns.
A short visual inspection can prevent avoidable problems once the car is back on the road. Look for rubbing marks, damaged wheels, and anything that suggests the current setup is tighter than expected. After installation, recheck pressure and pay attention to vibration, pull, or contact noises during the first miles of normal driving.
How often should tires on a 2018 Audi S4 be inspected?
Tires on a 2018 Audi S4 should be inspected regularly, not just when tread looks worn. A quick check for pressure loss, cuts, bulges, uneven wear, and sidewall damage should become routine, especially on a performance sedan where low-profile tires can be more vulnerable to curb impact and road damage.
Cars that are driven infrequently still need attention because age and storage conditions matter as much as mileage. Periodic inspection is a good habit before longer drives and after the car has been parked for extended periods. Catching early air loss or visible damage is far easier than dealing with a preventable roadside problem.
