2015 Audi S8 — Base Model

The 2015 Audi S8 Base Model shipped with 2 different factory tire sizes, depending on the wheel package it left the factory with (this can also reflect a staggered front/rear setup). Check your tire sidewall or door placard to confirm which one applies to your vehicle.

This trim shipped with more than one tire size (staggered fitment, front/rear, or optional wheel package). Confirm which one matches your vehicle by checking your tire sidewall or door placard.

265/35R21

Section width265 mm
Aspect ratio (sidewall height)35% (92.8 mm)
Rim diameter21"
Overall tire diameter~28.3"
Revolutions per mile~713

Compare prices at:

275/35R21

Section width275 mm
Aspect ratio (sidewall height)35% (96.3 mm)
Rim diameter21"
Overall tire diameter~28.6"
Revolutions per mile~706

Compare prices at:

What this size means for your Audi S8

On the 2015 Audi S8 Base Model, the factory 265/35R21 measures about 28.3″ in overall diameter with a 92.8 mm (3.7″) sidewall, and completes roughly 713 revolutions per mile. Its 35-series aspect ratio gives an ultra-low-profile, performance-oriented sidewall that favors steering precision over ride cushioning. In tire terms it is a large-diameter fitment.

The 265/35R21 and 275/35R21 roll within 0.3″ (1.1%) of each other in overall diameter, so they are interchangeable from a speedometer standpoint — the second size is an optional wheel package rather than a different rolling size.

Audi S8 tire sizes by year

See every Audi S8 year & trim →

How to read a tire size

A tire size like 225/45R17 breaks down into three parts: the first number is the section width in millimeters (the tire's width from sidewall to sidewall), the second is the aspect ratio — the sidewall's height as a percentage of that width — and the number after the "R" is the rim diameter in inches. A letter prefix (P or LT) indicates Passenger or Light Truck construction; its absence usually means Euro-metric sizing.

Some trucks and off-road tires instead use "flotation" sizing, like 37X12.50R17 — here the numbers are the tire's overall diameter and width in inches directly, with the rim diameter last.

Always verify against the tire information placard on your driver's-side door jamb or your owner's manual before purchasing — tire size can vary by factory option package even within the same trim.