The 2018 Audi S5 Sportback blends coupe-like styling with everyday hatchback practicality, making it one of the more versatile performance-minded Audis of its era. Buyers are usually balancing sharp road manners, modern appearance, and the refined character expected from an S model rather than chasing a purely vintage restoration outcome. Tire fitment centers on two radial sizes, 245/40R18 and 255/35R19, so the first step is confirming which wheel package is on the car. From there, the real choice is between 18-inch and 19-inch fitment, along with differences in tire series, sidewall presentation, and intended use such as street driving or specialty drag-oriented applications.
Which Tire Size Is Right for The 2018 Audi S5 Sportback
The 2018 Audi S5 Sportback uses two primary tire sizes, and the correct one depends first on wheel diameter. Both fitments are radial, but one is built around an 18-inch rim and the other around a 19-inch rim. Since both Premium Plus and Prestige models can use either size, the key step is confirming which wheels are actually on the car before comparing tire series, sidewall style, and performance intent.
The 245/40R18 size uses modern metric radial sizing: 245 is the nominal section width in millimeters, 40 is the aspect ratio, R indicates radial construction, and 18 is the rim diameter in inches. On the 2018 Audi S5 Sportback, this size suits the 18-inch wheel setup and keeps the selection focused on modern radial performance tires. Available choices include Blackwall, Redline, and raised white letter sidewalls, with offerings from BFGoodrich, Nitto, M&H Racemaster, and Pro-Trac across several tire series. This size is the right starting point if the car is on 18-inch wheels and the goal is to compare appearance, road use, and wheel-width compatibility within that fitment.
The 255/35R19 code follows the same modern metric radial format: 255 is the nominal section width in millimeters, 35 is the aspect ratio, R marks radial construction, and 19 is the wheel diameter in inches. For the 2018 Audi S5 Sportback, this size belongs to the 19-inch wheel setup and keeps the focus on low-profile radial performance tires. Current choices center on BFGoodrich products in Blackwall form, with multiple g-Force series available for buyers comparing tire character within the same fitment. This size is the one to evaluate when the car already has 19-inch wheels and the priority is matching that larger wheel package correctly.
Tire fitment is fairly straightforward across the covered 2018 Audi S5 Sportback sub-models because both Premium Plus and Prestige use the same two primary radial sizes. What matters most is confirming whether the car is wearing the 18-inch or 19-inch wheel setup before selecting a tire.
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2018 Audi S5 Sportback Premium Plus
The 2018 Audi S5 Sportback Premium Plus can use either of the two primary radial fitments for this model line. Tire selection therefore comes down to confirming the wheel diameter on the car, then comparing available tire series, sidewall treatments, and intended street or specialty use within that size.
The 2018 Audi S5 Sportback Prestige shares the same tire-fitment pattern, with both primary radial sizes applying depending on wheel package. The practical decision is not trim level but actual wheel diameter, followed by choosing the tire that best matches the car's appearance, driving use, and wheel-width requirements.
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 S5 Sportback Tires for Sale
Available tires for the 2018 Audi S5 Sportback span 245/40R18 and 255/35R19 radial fitments, with options from BFGoodrich, Nitto, M&H Racemaster, and Pro-Trac. Buyers can compare tire series, Blackwall versus Redline or raised white letter sidewalls, and wheel-width specifications within the correct size.
These FAQs focus on the two tire sizes used on the 2018 Audi S5 Sportback, how to confirm the right wheel fitment, and how to compare available radial tire choices for appearance, performance intent, and regular road use.
Tire Size & Fitment
What tire size fits a 2018 Audi S5 Sportback?
The 2018 Audi S5 Sportback uses two primary tire sizes: 245/40R18 and 255/35R19. Both are radial fitments, and the correct choice depends on whether the car has 18-inch wheels or 19-inch wheels installed.
Because both Premium Plus and Prestige models can use either size, trim name alone does not settle the question. Check the wheel diameter on the car first, then match the tire size to that wheel before comparing brands, sidewall styles, or tire series. That approach helps avoid treating the two fitments as interchangeable simply because they belong to the same model year and body style.
What size rim does a 2018 Audi S5 Sportback use?
A 2018 Audi S5 Sportback uses either an 18-inch rim with 245/40R18 tires or a 19-inch rim with 255/35R19 tires. Those are the two wheel diameters tied to the primary tire fitments for this vehicle.
Rim diameter is the first thing to confirm before choosing a tire, since an 18-inch tire cannot be mounted on a 19-inch wheel and vice versa. It also helps to review wheel width, especially if the car has aftermarket wheels. Once the wheel diameter is confirmed, the buying decision becomes much simpler because the tire comparison stays within the correct fitment group.
Do all 2018 Audi S5 Sportback sub-models use the same tire size?
The 2018 Audi S5 Sportback Premium Plus and Prestige share the same overall fitment pattern, with both 245/40R18 and 255/35R19 used across the model range. The difference is not the sub-model itself, but which wheel package is on the car.
That means the safest way to identify the right tire is to inspect the actual wheels rather than rely only on trim level. A Premium Plus may be on 18-inch or 19-inch wheels, and the same is true for a Prestige. Once wheel diameter is confirmed, the remaining choice is between the tire options available in that exact size.
Choosing the Right Tire
What should I consider when choosing a 245/40R18 or 255/35R19 tire for a 2018 Audi S5 Sportback?
Start with the correct size for the wheel on the car: 245/40R18 for 18-inch rims or 255/35R19 for 19-inch rims. After that, compare construction, wheel-width compatibility, tire series, sidewall style, and any specialty attributes that affect how the car will be used.
Some choices are geared toward mainstream street performance, while others are more specialized, such as a drag-oriented radial in 245/40R18. Sidewall presentation also changes the look, especially where Blackwall, Redline, or raised white letter options are available. Matching the tire to both the wheel setup and the car's intended use usually matters more than choosing by brand name alone.
What sidewall styles are available for 2018 Audi S5 Sportback tires?
Sidewall choice depends on tire size. In 245/40R18, available sidewall styles include Blackwall, Redline, and RWL, while the 255/35R19 options shown here are Blackwall only.
That gives the 18-inch fitment more visual variety if the goal is to add a stronger styling statement. A Blackwall keeps the look understated and contemporary, while Redline or raised white letter sidewalls push the car in a more custom or enthusiast-oriented direction. The right choice depends on whether appearance is a major priority or whether the focus stays on a more subtle factory-inspired presentation.
What brands offer tires for the 2018 Audi S5 Sportback?
Tires for the 2018 Audi S5 Sportback are available from BFGoodrich, Nitto, M&H Racemaster, and Pro-Trac, depending on size. The 245/40R18 fitment has the broadest mix, while 255/35R19 centers on BFGoodrich offerings.
Brand alone should not be the only filter. It helps to compare each option by tire series, sidewall treatment, wheel-width specification, and whether the tire is intended for regular street driving or a more specialized purpose. Once the correct wheel diameter and tire size are settled, those factors make it easier to narrow the field without assuming every product in the same size serves the same role.
Restoration & Appearance
Which tire should I choose for a period-style 2018 Audi S5 Sportback?
A period-style approach on a 2018 Audi S5 Sportback usually starts by staying with the wheel diameter already on the car, then choosing a tire that supports the look you want within 245/40R18 or 255/35R19. Since this is a modern performance Audi, the appearance question is more about subtle versus custom presentation than vintage restoration accuracy.
Blackwall tires keep the look closest to a restrained late-model sport sedan style, while Redline or raised white letter options in 245/40R18 create a more deliberate visual statement. If exact originality matters, compare the car against window-sticker, dealer-order, or marque-specific references before choosing a nonstandard sidewall treatment.
How does tire construction affect the appearance of a restored 2018 Audi S5 Sportback?
On a 2018 Audi S5 Sportback, construction is less about bias-ply versus radial and more about staying within the correct modern radial fitment. The visual difference usually comes from profile, sidewall treatment, and wheel diameter rather than a change in basic tire construction.
A 245/40R18 setup can open the door to Redline or raised white letter styling, while 255/35R19 choices shown here maintain a Blackwall look. That means the car's final appearance is shaped mostly by the combination of wheel size and sidewall style. Keeping the tire matched to the wheel package helps preserve the balanced, performance-oriented stance the S5 Sportback is known for.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 2018 Audi S5 Sportback?
Yes. Modifications such as aftermarket wheels, offset changes, suspension lowering, or body alterations can affect tire fitment on a 2018 Audi S5 Sportback even when the tire size matches one of the standard fitments. The car's two primary sizes are tied to 18-inch and 19-inch wheel setups, so wheel changes matter immediately.
A modified car should be checked for wheel width, clearance at full steering lock, and space around the fender and suspension before settling on a tire. That is especially important if the car no longer uses stock-style wheels. A tire that suits one S5 Sportback may need closer measurement on another if the stance or hardware has been changed.
What should I inspect before driving a 2018 Audi S5 Sportback on new tires?
Before road use, inspect wheel condition, valve stems, tire pressure, and basic clearance around the fenders and suspension. It is also smart to confirm that all four tires match the intended size and that the tires are mounted on the correct 18-inch or 19-inch wheels for the fitment being used.
A quick road-use check should also include looking for uneven wear, sidewall damage, cuts, or signs of air loss after installation. If the car has been modified or has not been driven much lately, pay extra attention to alignment feel and any rubbing during low-speed turning. Those checks help catch setup issues before they become more serious on the road.
How often should tires on a 2018 Audi S5 Sportback be inspected?
Tires on a 2018 Audi S5 Sportback should be inspected regularly, not just when tread looks low. Performance-oriented cars can be sensitive to alignment changes, air pressure variation, and shoulder wear, so routine visual checks are worthwhile even when mileage is modest.
Look for uneven tread wear, cracking, punctures, bulges, and slow air loss, and include the inner sidewall when possible rather than checking only the visible outer face. Cars that sit for longer periods still need attention because age and storage conditions can affect tire condition. Frequent inspection is one of the simplest ways to protect both fitment quality and road manners.
