How-to: do Mercedes Sprinter w906 NCV3 Tyre/Tire Size Coding using a cheap Thinkdiag obd2 scanner.
Here we just want to share user’s experience of changing tyre size, and resolving the resulting mismatch in speedo and mileage.
If you put on larger than stock tyres, the larger circumference means the speedo will be reading lower than before at the same actual speed, and the mileage (according to the ECU) will be lower than actual.
Stock tyre size on original Sprinter 906/NCV3 2018 OM651 facelift LWB was 235/65/R16
Replaced with BF Goodrich: 245/70/R17
Speedo error of -8.12%. Not ideal.
The solution is to find a way of changing the tyre size in the ECU.
Autel AP200 doesn’t have the capability.
The user was exploring using a Tactrix Openport 2.0 + Xentry setup, but is way too much work just to change tyre sizes.
Then he has used a ThinkDiag + accompanying app.
Note. You need to use with an Android device for this. iOS ThinkDiag app doesn’t have the required coding capability.
Here is where to find the option to change tyre sizes (front tyres and rear tyres are a separate parameter).
Go to System Selection-> Body->EZS-> Variantenkodierung (Variant coding)
Select the new tyre size closest to yours. Hit OK for each, confirm the new values are shown, then write the coding.
Strangely the ECU coded circumference sizes don’t align with those determined by willtheyfit.com
So I chose the available size that matched closest. 0.12% out, I’ll take that.
RH8 (LT245/75R16 , 2360mm)
My new tyres: BF Goodrich: 245/70/R17
New programmed tyres: 245/75/R16
If there isn’t a suitable tyre size available to select, you might consider programming in new sizes. It can be done easily with DTS Monaco or Vediamo.
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