The 2018 Audi S5 sits in the modern grand-touring side of Audi performance, blending sharp coupe or cabriolet styling with everyday drivability and the more athletic character expected from the S line. That balance matters when choosing tires, because this S5 uses radial fitments in two low-profile metric sizes: 245/40R18 and 255/35R19. The decision is less about vintage-style construction and more about confirming the wheel setup, then choosing the right mix of blackwall, redline, or raised white letter appearance along with the tire series that matches how the car is driven. Owners should verify their exact wheel diameter first, especially on cars that may have changed wheels over time.
Which Tire Size Is Right for The 2018 Audi S5
The 2018 Audi S5 uses two primary tire sizes, and the first step is confirming whether the car is on 18-inch or 19-inch wheels. Both sizes are radial metric fitments used across the S5 range, so the real decision comes down to wheel diameter, tire style, and the product characteristics that best match the car's current setup and intended use.
Fit(s): Premium Plus Cabriolet, Premium Plus Coupe, Prestige Cabriolet, and Prestige Coupe
Construction: Radial|Rim: 18 in
245/40R18 is a modern metric radial size in which 245 is the section width in millimeters, 40 is the aspect ratio, R identifies radial construction, and 18 is the wheel diameter in inches. On the 2018 Audi S5, this size supports the car's contemporary low-profile handling character on an 18-inch wheel. Available choices include blackwall performance-oriented options as well as Pro-Trac Street Pro III versions with redline or raised white letter sidewalls. This size is the one to evaluate when the car is equipped with 18-inch wheels and the goal is to balance fitment accuracy with appearance and intended road use.
Fit(s): Premium Plus Cabriolet, Premium Plus Coupe, Prestige Cabriolet, and Prestige Coupe
Construction: Radial|Rim: 19 in
255/35R19 is also a modern metric radial size, with a 255-millimeter section width, a 35-series profile, radial construction, and a 19-inch rim diameter. For the 2018 Audi S5, it represents the lower-profile 19-inch wheel fitment and should be matched to the actual wheel diameter on the car before selection. The available product range in this size centers on BFGoodrich g-Force series tires in blackwall form, giving buyers a more focused set of choices. This size deserves close attention when the S5 has factory-style or aftermarket 19-inch wheels and clearance should remain consistent with that setup.
Tire fitment is straightforward across the 2018 Audi S5 lineup because each covered sub-model can use the same two radial sizes. The key is not trim level as much as confirming whether the car is currently fitted with 18-inch or 19-inch wheels before choosing a tire.
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2018 Audi S5 Premium Plus Cabriolet
The 2018 Audi S5 Premium Plus Cabriolet uses the same two radial size choices found elsewhere in the S5 range, so wheel diameter is the main fitment question. Tire selection then becomes a matter of matching the current 18-inch or 19-inch setup to the preferred sidewall style and tire series.
The 2018 Audi S5 Premium Plus Coupe shares the same basic tire-fitment path as the other covered S5 versions, with both 18-inch and 19-inch radial sizes in play. That makes wheel confirmation especially important before comparing blackwall, redline, or raised white letter options in the available sizes.
The 2018 Audi S5 Prestige Cabriolet follows the same fitment pattern as the rest of the model line, using either of the two primary radial sizes depending on wheel diameter. Once the wheel size is confirmed, the choice shifts to product style, construction details within the radial category, and how the car is actually driven.
The 2018 Audi S5 Prestige Coupe also shares the same two-size radial fitment approach, so there is no separate trim-specific tire size to sort out first. Buyers should focus on confirming the wheel diameter already on the car, then compare the available series and sidewall presentation within that correct size.
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 Tires for Sale
Available 2018 Audi S5 tire choices center on 245/40R18 and 255/35R19 radial fitments from BFGoodrich, Nitto, M&H Racemaster, and Pro-Trac. The product grid lets buyers compare blackwall performance tires alongside select redline and raised white letter options, with some variation in tire series, rim-width compatibility, load figures, and intended use.
These 2018 Audi S5 tire FAQs focus on the two correct sizes, 18-inch versus 19-inch wheel fitment, available radial choices, sidewall styling, and the practical checks worth making before road use.
Tire Size & Fitment
What tire size fits a 2018 Audi S5?
The 2018 Audi S5 uses two primary radial tire sizes: 245/40R18 and 255/35R19. Those sizes apply across the covered Premium Plus and Prestige Coupe and Cabriolet versions, so the main fitment difference is wheel diameter rather than sub-model name.
The practical next step is checking whether the car is actually on 18-inch or 19-inch wheels before choosing a tire. A car may no longer be on its original wheel setup, and that matters more than trim level when selecting between these two sizes. Once wheel diameter is confirmed, compare the available tire series, sidewall style, and rim-width requirements within the matching size.
What size rim does a 2018 Audi S5 use?
A 2018 Audi S5 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 fitment goes with an 18-inch wheel, while the 255/35R19 fitment goes with a 19-inch wheel.
Rim diameter should be confirmed before anything else because neither tire size can be mounted correctly on the other wheel diameter. It is also worth checking wheel width, especially if the S5 has aftermarket wheels, since some available tires include specific rim-width ranges. That extra step helps narrow the product choices and avoids selecting a tire that suits the size code but not the actual wheel.
Do all 2018 Audi S5 sub-models use the same tire size?
The covered 2018 Audi S5 sub-models share the same two tire-size options rather than having separate trim-specific sizes. Premium Plus Cabriolet, Premium Plus Coupe, Prestige Cabriolet, and Prestige Coupe can all use 245/40R18 or 255/35R19, depending on wheel diameter.
That means sub-model identification alone does not finish the fitment job. The owner still needs to confirm the wheel diameter currently installed on the car, because the same S5 trim may be running either setup. Looking at the sidewall on the existing tires or measuring the wheel is the best way to separate an 18-inch fitment decision from a 19-inch one before comparing products.
Choosing the Right Tire
What should I consider when choosing a 245/40R18 or 255/35R19 tire for a 2018 Audi S5?
Start with the correct size for the wheel already on the 2018 Audi S5, then compare construction details within the available radial options. The 245/40R18 selection includes a broader mix of brands and sidewall styles, while 255/35R19 choices are more concentrated around BFGoodrich g-Force series products.
After the size is settled, consider how the car is used and how much appearance matters. Some buyers will want a blackwall performance look, while others may prefer redline or raised white letter styling in 245/40R18. Rim-width compatibility, load figures stated with inflation pressure when shown, and the tire's intended character all deserve a close look before making the final choice.
What sidewall styles are available for 2018 Audi S5 tires?
Sidewall style depends on the tire size and product chosen for the 2018 Audi S5. Blackwall options are available in both 245/40R18 and 255/35R19, while the 245/40R18 size also includes Pro-Trac Street Pro III versions with redline and raised white letter sidewalls.
That gives the 18-inch fitment more appearance variety than the 19-inch fitment. Buyers who want a more traditional or custom-styled presentation may gravitate toward redline or raised white letter options, while those keeping a more understated modern look may prefer blackwall. The key is to treat sidewall styling as a secondary choice after the correct wheel diameter and tire size have been confirmed.
What brands offer tires for the 2018 Audi S5?
Tires for the 2018 Audi S5 are available from BFGoodrich, Nitto, M&H Racemaster, and Pro-Trac. Brand choice varies by size, with 245/40R18 offering the widest spread of options and 255/35R19 focusing on BFGoodrich performance-oriented choices.
Brand should be considered alongside the actual tire series, sidewall presentation, and wheel compatibility rather than as a shortcut to the right answer. For example, one buyer may be comparing a drag-focused 245/40R18 option against street-oriented radial choices, while another simply wants a blackwall 19-inch fitment. Keeping the comparison centered on size, intended use, and construction details leads to a better selection process.
Restoration & Appearance
Which tire should I choose for a period-style 2018 Audi S5?
A period-style 2018 Audi S5 usually starts with keeping the correct modern radial size for the wheel on the car, either 245/40R18 or 255/35R19. From there, the most appearance-conscious choices tend to come from the 245/40R18 offerings, which include blackwall, redline, and raised white letter sidewall treatments.
Because the S5 is a recent performance grand-touring car rather than a vintage restoration subject, the appearance decision is more about preserving the car's character than recreating an antique tire look. Wheel diameter still comes first, and buyers who want a closer-to-stock visual presentation should compare sidewall style carefully before moving toward more expressive alternatives such as redline or raised white letter tires.
How does tire construction affect the appearance of a restored 2018 Audi S5?
On a 2018 Audi S5, construction does not create a bias-ply-versus-radial appearance choice because the primary fitments are radial. The visual difference comes more from the size selected for the car's wheel diameter and the sidewall treatment, particularly in 245/40R18 where blackwall, redline, and raised white letter options are available.
That means appearance planning should focus on how the tire complements the wheel and overall stance rather than on switching construction types. A blackwall tire keeps a contemporary, understated look, while redline or raised white letter versions make the car look more personalized. Any appearance change still needs to stay within the correct S5 size and wheel setup so the styling choice does not create a fitment problem.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 2018 Audi S5?
Yes, modifications can affect tire fitment on a 2018 Audi S5 even when the tire size itself looks correct. Aftermarket wheels, suspension lowering, spacer use, or brake and body changes can alter the wheel width, offset, and the available clearance around a 245/40R18 or 255/35R19 tire.
A modified S5 should be checked at full steering lock and through suspension travel before settling on a tire choice. Wheel diameter is only part of the picture; width and offset matter as well. Keeping an eye on fender clearance, inner suspension clearance, and the tire maker's stated rim-width guidelines helps prevent a fitment that works on paper but crowds the car once installed.
What should I inspect before driving a 2018 Audi S5 on new tires?
Before driving a 2018 Audi S5 on new tires, inspect the wheel diameter, wheel condition, lug hardware, and inflation pressure, then confirm the tire size matches the wheel on the car. It is also smart to look for uneven suspension wear or alignment issues that could affect how the new tires behave.
A short visual check after installation can prevent larger problems later. Make sure there is no rubbing at the fender or inner wheelhouse, and watch for any immediate air loss, vibration, or steering pull once the car is moving. On a performance-oriented car like the S5, proper balance and alignment matter just as much as the correct size when the goal is stable road manners.
How often should tires on a 2018 Audi S5 be inspected?
Tires on a 2018 Audi S5 should be inspected regularly, not just when tread looks low. Check them for pressure loss, cuts, bulges, irregular tread wear, and sidewall damage as part of routine ownership, especially because low-profile tires can be more sensitive to road impacts and wheel-condition issues.
Inspection becomes even more important if the car is driven seasonally or sits for long periods. A stored S5 can develop age-related tire concerns even when tread depth still looks usable. Looking over the tires before longer drives, and after any pothole strike or curb contact, helps catch problems early and confirms the wheels and tires are still working together as intended.
