The 2018 Audi A8 Quattro sits at the top of Audi’s full-size luxury sedan lineup, blending long-wheelbase comfort with the all-weather confidence expected from a Quattro flagship. Buyers looking at one today are usually balancing premium road manners, appearance, and precise fitment rather than chasing a purely restoration-driven tire decision. Tire selection for this exact model centers on three radial sizes: 255/45R19, 265/40R20, and 275/35R21, with fitment varying by sub-model and wheel package. That makes wheel diameter and exact trim confirmation especially important. Once those are settled, the focus shifts to maintaining proper proportions, load-carrying confidence, and clearance on a sophisticated luxury chassis.
Which Tire Size Is Right for The 2018 Audi A8 Quattro
Three primary tire sizes apply to the 2018 Audi A8 Quattro, and they span three different rim diameters: 19, 20, and 21 inches. The first step is confirming the exact sub-model and, just as importantly, the wheel diameter currently on the car, since tire choice follows the wheel package rather than one universal fitment across every A8 Quattro configuration.
Sub-model fitment matters on the 2018 Audi A8 Quattro because the available tire sizes are not identical across the lineup. Confirming whether the car is an L 3.0 or L 4.0, then matching that to the actual wheel diameter on the vehicle, keeps the tire search focused on the right fitment path.
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2018 Audi A8 Quattro L 3.0
The 2018 Audi A8 Quattro L 3.0 can use 19-inch, 20-inch, or 21-inch radial fitments depending on the wheel setup on the car. That makes wheel confirmation the key step before comparing tires, especially if appearance, ride character, or previous wheel changes may have altered what is currently installed.
The 2018 Audi A8 Quattro L 4.0 uses the larger 20-inch and 21-inch radial fitments rather than the 19-inch option. Tire selection starts with confirming which of those two wheel diameters is present, then choosing a size that preserves the car’s intended proportions and clearance.
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.
Frequently Asked Questions
Questions for the 2018 Audi A8 Quattro usually come down to identifying the correct tire size by sub-model and wheel diameter, then understanding how each metric radial size relates to ride, appearance, and fitment checks before road use.
Tire Size & Fitment
What tire size fits a 2018 Audi A8 Quattro?
The 2018 Audi A8 Quattro uses three radial tire sizes: 255/45R19, 265/40R20, and 275/35R21. The exact size depends on the sub-model and wheel package, so there is not one universal tire size for every version of this sedan.
The practical first step is to confirm the sub-model and the wheel diameter actually on the car. An A8 Quattro L 3.0 can use 19-, 20-, or 21-inch fitments, while the L 4.0 uses 20- or 21-inch sizes, so reading the current tire sidewall and verifying the wheel before ordering avoids an expensive mismatch.
What size rim does a 2018 Audi A8 Quattro use?
The 2018 Audi A8 Quattro uses 19-inch, 20-inch, or 21-inch rims depending on the tire size fitted to the car. Those correspond to 255/45R19, 265/40R20, and 275/35R21, all in radial construction.
Because the rim diameter changes with the tire size, wheel confirmation comes before anything else. The tire sidewall and wheel itself should agree on diameter, and any car with aftermarket wheels should be checked carefully so the replacement tire matches the actual wheel on the vehicle rather than only the model name.
Why does the 2018 Audi A8 Quattro have more than one tire size?
More than one tire size applies because the 2018 Audi A8 Quattro was fitted with different wheel diameters across its covered configurations. The L 3.0 spans 19-, 20-, and 21-inch fitments, while the L 4.0 uses 20- and 21-inch setups.
That means tire selection is driven by the exact sub-model and wheel package, not just by year, make, and model alone. Even when the overall tire dimensions stay relatively close, the wrong rim diameter will not work, so checking the current wheel and tire markings is the safest starting point before comparing replacement options.
Choosing the Right Tire
What should I consider when choosing a 255/45R19 tire for a 2018 Audi A8 Quattro?
A 255/45R19 tire uses a 255-millimeter section width, a 45-series aspect ratio, and fits a 19-inch rim. On a 2018 Audi A8 Quattro, that size appears on the L 3.0, so the first consideration is confirming that the car actually has the 19-inch wheel package.
Once the size is confirmed, focus on maintaining the correct load capability, overall proportions, and clearance for a large luxury sedan. Any car that has had wheel, suspension, or alignment changes deserves an extra check, since replacing by size alone does not account for altered offsets, ride height, or previous modifications.
What should I consider when choosing a 265/40R20 tire for a 2018 Audi A8 Quattro?
The 265/40R20 size is a metric radial with a 265-millimeter section width, a 40-series profile, and a 20-inch rim diameter. It is used on both the 2018 Audi A8 Quattro L 3.0 and L 4.0, making it one of the broader fitment points within this model range.
Selection should start with confirming the 20-inch wheel, then checking that the replacement tire suits the car’s weight, intended driving use, and present wheel setup. Since this size sits between the 19- and 21-inch fitments, owners often want to preserve the existing ride and appearance balance rather than unintentionally changing the car’s stance or clearance.
What should I consider when choosing a 275/35R21 tire for a 2018 Audi A8 Quattro?
A 275/35R21 tire is a low-profile metric radial that combines a 275-millimeter section width with a 35-series aspect ratio on a 21-inch rim. On the 2018 Audi A8 Quattro, it applies to both the L 3.0 and L 4.0 when equipped with the largest wheel setup.
Because this fitment uses the largest rim diameter in the range, careful wheel verification is essential before replacing it. Owners should also inspect fender and suspension clearance, especially on cars with aftermarket wheels or altered ride height, since low-profile 21-inch fitments leave less room for errors in wheel specification or vehicle setup.
Restoration & Appearance
Does correct tire fitment matter for a 2018 Audi A8 Quattro restoration or preservation project?
Correct tire fitment still matters even on a modern luxury sedan like the 2018 Audi A8 Quattro. Using the proper 19-, 20-, or 21-inch size for the actual wheel package helps preserve the car’s intended stance, sidewall proportion, and overall visual balance.
Appearance on an A8 is tied closely to wheel diameter and profile, so an incorrect substitute can make the car look noticeably off even before road behavior is considered. For owners keeping the car in original-style condition, matching the existing wheel setup and avoiding unnecessary size changes is usually the cleanest approach.
How does tire size affect the appearance of a 2018 Audi A8 Quattro?
Tire size has a visible effect on the 2018 Audi A8 Quattro because each fitment pairs a different sidewall profile with a different wheel diameter. The 255/45R19, 265/40R20, and 275/35R21 sizes all keep a similar overall diameter range, but they present the car differently.
A taller sidewall on a 19-inch setup gives a fuller tire presence, while the 21-inch fitment creates a more wheel-dominant look with a lower-profile sidewall. Buyers trying to preserve the car’s established appearance should replace like for like unless they are intentionally changing wheel style and have confirmed compatibility first.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 2018 Audi A8 Quattro?
Yes, modifications can affect tire fitment on a 2018 Audi A8 Quattro even when the nominal tire size seems correct. Aftermarket wheels, altered offsets, suspension changes, or ride-height adjustments can all change how a 255/45R19, 265/40R20, or 275/35R21 tire sits in the wheel opening.
That is why replacement should never rely only on the model name if the car has been changed from stock wheel or suspension configuration. A quick check of wheel diameter, width, offset, and visible clearance at the fender and suspension helps prevent rubbing, mismatch, or uneven behavior after new tires are installed.
What should I inspect before driving a 2018 Audi A8 Quattro on new tires?
Before driving a 2018 Audi A8 Quattro on new tires, inspect inflation pressure, wheel fastener torque, valve condition, and basic tire seating on the rim. It is also smart to confirm that all four tires match the intended size and that no shipping damage, cuts, or obvious sidewall defects are present.
A short, careful road test should follow, with attention to vibration, pulling, rubbing, or warning messages that suggest a setup issue. Large luxury sedans are sensitive to wheel and tire inconsistencies, so checking alignment history and making sure the chosen size matches the actual wheel package can prevent problems from showing up later.
What should I check before a longer drive in a 2018 Audi A8 Quattro?
Before a longer drive, the 2018 Audi A8 Quattro should have its tire pressures checked cold and all four tires inspected for tread wear, cracking, punctures, bulges, or slow air loss. The correct size should also be confirmed visually so the car is not running a mismatched replacement from a previous service or wheel change.
Longer trips put more heat into the tires, so any weakness in an aging or damaged tire becomes more important. A car that spends long periods parked deserves extra attention to age-related condition, and any sign of uneven wear should prompt an alignment or suspension check before relying on the vehicle for distance driving.
