AO and AO1 for Audi
The tyre was developed for, and approved by, Audi. Michelin, Pirelli and Continental all list AO, AO1 and RO1 as Audi’s marks. Pirelli writes that marked tyres “are now requested by all top car manufacturers”.
What to do with it
Read the digit or letters after AO too: they are part of the mark. Whether your Audi has to keep AO tyres is something none of these three pages says, so this page cannot tell you either. When replacing marked tyres Michelin writes that “it is therefore important to specify the same tyre as that approved by the car manufacturer”.
- What it looks like
- The letters AO moulded on the sidewall, alone or as AO1 or AO2; RO1 and RO2 are listed for Audi too. All three lists write AO with the letter O. None of the three says where on the sidewall it sits: our drawing puts it after a size only to show it.
- Set by
- No regulation we read defines it: it is the tyre makers’ own marking, so the makers are the sources.
In detail
- In all three lists, read on 2026-10-16: AO, AO1 and RO1. RO2 is on Pirelli’s and Continental’s lists; AO2 and RO only on Michelin’s; AOE, AOE1, R0 and RE0 only on Pirelli’s.
- Continental’s key gives every one of its Audi rows the same meaning: “AO — AUDI”, “AO1 — AUDI”, “RO1 — AUDI”, “RO2 — AUDI”. None of the three pages says what separates AO from AO1, or AO from RO1.
- AOE: only Pirelli’s list has it, and Pirelli does not say what the E adds. With one tyre maker and no stated meaning, this page does not call it a run-flat mark. Compare MOE, which Continental labels “MERCEDES-BENZ RUNFLAT”.
- The same car maker can have different marks at different tyre makers: Audi’s are nearly the same in all three lists, but Ferrari’s are F to F04 on Pirelli’s list and K1 to K3 on Michelin’s.
- Pirelli gives its reason for marked tyres: “Every car is different. They have different weights and specific configurations.”
What it does not mean
AO is not a size, load or speed code and not a regulatory mark: Michelin notes that approval by a car maker “is not a mandatory process”, unlike the type approval every tyre needs. All three lists write it with the letter O, unlike Porsche’s N0, which they write with a zero.
Markings that go with it
Sources
Each document was fetched and read on the date shown; the clause is the one that sets this marking.
- Michelin (UK): All you need to know about MICHELIN-developed marked tyres — OE marking table, row Audi: AUDI: “AO - AO1 - AO2 - RO - RO1”. “Marked tyres are the result of a specific demand expressed by individual car manufacturers.” Checked 2026-10-16.
- Pirelli (UK): Custom-made tyre marking — Original Equipment marking, letter A: Under “AUDI”: “AO”, “AO1”, “AOE”, “AOE1”, “R0”, “RO1”, “RO2”, “RE0”. “Every car is different. They have different weights and specific configurations.” Checked 2026-10-16.
- Continental (Singapore): Original Equipment — Manufacturer Tyre Markings — Manufacturer Tyre Markings, OE key: “AO — AUDI”; “AO1 — AUDI”; “RO1 — AUDI”; “RO2 — AUDI”. Checked 2026-10-16.