Audi A6 Allroad: Two Tire Sizes Available

Hello everyone,

I can't find anything using the search function.

My Allroad has a second set of tire sizes programmed into it and is adjusted for the 225/65 R17 AT3 (All-Terrain) tires, which it received instead of winter tires when it was originally delivered.

The speedometer always worked correctly, and it had the advantage that I could use large 19-inch tires as summer tires without having to change them seasonally. But now, that's exactly the question!

How do I switch from the second tire size to the first one?

Unfortunately, this is the first time I'm taking the car to the TÜV (technical inspection) with the standard tires because all my other tire sets are worn out. The overly zealous inspector noticed that two very large wheel and tire combinations are registered but not currently installed, and he asked me if I wouldn't need a speedometer recalibration for the standard tires.

"To that, I replied, no, because I have two sets of tire circumference values coded in." Then, when I tried to show him (on the AVL tester) which circumferences were entered and how to switch between them, I completely drew a blank.

Zu Hause angekommen habe ich mit VCDS nachgesehen. Situation:

- In STG 17, a second pair is encoded.
- However, in the vehicle registration document (Fahrzeugschein), I only find the middle and maximum wheel circumference values for the first axle, with the values specified for the standard tire size. (MWB 29-0 = 2065 & MWB 29-1 = 2106)
- The speedometer shows a certain speed with standard tires, but when driving at 100 km/h, the GPS indicates a whopping 12 km/h less than what the speedometer displays, especially when using worn-out AT3 tires.

So:
1. In which technical manual can I find the 2168 (average) and 2212 (maximum) values for the second set of tire circumferences?
2. How do I change the tire rotation when changing tires?

Maybe I completely misunderstood something, and I'm always happy to learn more.

Best regards.

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Hi Bo,

It should involve coding within the instrument cluster (control unit address 17).
As far as I know, depending on which of the two tire sizes is fitted, either a value is added or subtracted. The encoding is essentially a bitmask.

I might be able to tell you more using Autoscan.

When you hover the mouse cursor over the encoding input field, a tooltip appears with information about the old encoding function.

Instead, your instrument cluster likely has a long coding sequence; simply click through the options in the LCode menu.

Best regards, Rainer.

Thank you for the quick response!

Unfortunately, no long-form coding is possible.

Theoretically, when using the standard coding procedure, you would need to enter +8 for the second tire size setting. I understood that this setting indicates there are two tires of a certain size, but that the actual value is adjusted elsewhere. However, I'll try entering -8 and see if it then displays the correct speed on the speedometer.


Somewhere, those different values must be stored within the MWB system. I'm going crazy trying to figure this out.

Autoscan, screenshots of the coding menu, customization options, and vehicle data sheet (VDS).

I would have expected the second set of data to be found in MWB sections 29-3 and 29-4. I'm also not sure where or how to enter these values.

Hi,

Switching via coding +0008: second tire circumference pair, or not.

Have you already searched for terms like "second" or "tire" within the measurement values? You can type them into the search bar at the top of the list.

Perhaps it's also possible to simply switch between two fixed wheel circumferences?

Quote:

VCDS Version: DRV 19.6.1.0

I would first update.

Best regards, Rainer.

dieselschrauber wrote:

Quote: VCDS Version: DRV 19.6.1.0 I would first update. Best regards, Rainer

No internet in the workshop!

Now that I have it at home, because of the data, then I'll do it if you insist. But my youngest VAG vehicle is from 2014. I guess it probably doesn't matter anyway.

Ste.Bo wrote:

Unfortunately, this is the first time I'm taking the car to the TÜV (technical inspection) with the standard tires because all my other tire sets are worn out. The overly zealous inspector noticed that two very large wheel and tire combinations are registered but not currently installed, and he asked me if I need a speedometer recalibration for the standard tires.

Tire and wheel combinations are only permitted (and can be registered) if...

1. The rolling circumference is identical to the standard configuration.
2. A speedometer calibration is required, which will then allow the standard combination to be implemented.


"Given this, I don't understand the examiner's objection. Does your rolling circumference differ significantly from the combinations you are driving, or which combinations are registered?"

vag-driver wrote:

Tire and wheel combinations are only permitted (and can be registered) if... 1. The rolling circumference is identical to the standard configuration. 2. A speedometer calibration is required, which will then allow the standard combination to be implemented. Given this, I don't understand the examiner's objection. Does your declared rolling circumference differ significantly from the combinations you are driving, or which combinations are registered?

Yes, it's very different!

- The smallest registered tire size is the original M&S 215/55R17 with a circumference of 2032 mm.
- The largest registered dimension (recorded at delivery, with reference) is 2212 mm.

The speedometer is correct for the larger tire size. However, no speedometer calibration was performed; instead, a second tire size was specified and activated by the dealer. According to this dealer, this is possible up to a mileage of 100 kilometers using the workshop tester.

However, it seems that an error occurred because the return path does not work.

Now, with the original summer tires (size 225/55R17), it displays a value that is far too low. With the 215s, it would be even lower.

Hi Bo,

So, your AI coding is 7273058.

Relevant to the tire issue is 7273, which breaks down into 4096 + 2048 + 1024 + (0 * 512) + (0 * 256) + (0 * 128) + 64 + 32 + (0 * 16) + 8 + (0 * 4) + (0 * 2) + 1.

So, the second tire combination is currently active. To activate the other one, you need to subtract 8, which means that 7265 is the new first part of the code.

The complete code is then: 7265058.

"Have you checked that yet? It's tricky because only the first 4 digits are a bitmask, so simply subtracting 8 from the entire encoding won't work..."

Best regards, Rainer.

dieselschrauber wrote:

Hi Bo, So, your AI coding is 7273058. Relevant for the tire issue is 7273, which breaks down into 4096 + 2048 + 1024 + (0 * 512) + (0 * 256) + (0 * 128) + 64 + 32 + (0 * 16) + 8 + (0 * 4) + (0 * 2) + 1. So, the second tire combination is currently active. To activate the other one, you need to subtract 8, which means that 7265 is the new first part of the code. The complete code is then: 7265058. "Have you checked that yet? It's tricky because only the first 4 digits are a bitmask, so simply subtracting 8 from the entire encoding won't work..." Best regards, Rainer

Hello Rainer,

sorry für die späte Rückmeldung es hat nicht funktioniert. Ich habe es beim anderen Allroad in der Familie probiert, da geht das umschalten problemlos. IcI have given up.

Best regards and Merry Christmas.

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Thank you for the feedback! It would also be interesting to know if the other Allroad is programmed in the same way.

dieselschrauber wrote:

Thank you for the feedback! It would also be interesting to know if the other Allroad is coded in the same way.

The other one has an AAC codec, mine doesn't, so it's encoded differently anyway.

Regards,

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.