2-Ventiler Umbauten: Welche Reifen passen und was darf ich fahren?

2-Valve Conversions: Which Tires Fit and What Am I Allowed to Ride?

Tires play a crucial role in BMW 2-valve conversions. However, I won't be evaluating individual tire types and brands here. Generally, the reason for mounting scrambler tires is not that people want to ride off-road. It should be clear to everyone that a low-profile sport tire will always perform better than a 4.50 Shinko bias-ply tire or a TKC80 scrambler tire.
 
For tire conversions, especially when changing the size, there are usually no reports or non-objection certificates from BMW or the tire companies for the old boxers. Here, the TÜV (Technical Inspection Association) is required to check the tires for their suitability in conjunction with the respective motorcycle. The registration then takes place via individual approval. Fortunately, there are many TÜV inspection engineers who have a great affinity for motorcycles and the corresponding expertise to evaluate such a conversion and ultimately approve it. You need such an inspector!
However, there are unfortunately also inspectors who do not want to take on this responsibility and do not want to make any entries without a report or a non-objection certificate. If the vehicle is a 300 km/h S1000RR, I can still understand that to some extent. But not for our beloved BMW 2-valve models, which are miles away from such speed ranges. If you encounter such an inspection engineer, I would advise you to stop and try another TÜV office.

But even if you have found a competent inspector, there are rules you must follow.
  1. The tire size must match the rim size. Usually, tire manufacturers state in their technical tables which rim dimensions are required for the tire in question.
  2. The speed index of the tires must be at least 10 km/h higher than the maximum speed stated in the vehicle documents.
  3. An exception applies to M&S tires. These winter tires are approved for a maximum of 160 km/h and may also be mounted on vehicles whose registered maximum speed is higher. A label "Max. 160km/h" must be affixed to the speedometer (sticker).   
  4. The clearance of the tires must be ensured. Here we assume a minimum distance of vehicle components to the side of the tire of 5mm. Lengthwise, it must be noted that the tire grows at higher speeds. Here we observe a minimum distance of 10mm.
Here is a list of tire combinations that we use on our SE Concept Bikes. As mentioned, we install these tires and then have the complete vehicles approved by our TÜV inspection center. However, this list does not guarantee that your local TÜV office will behave in the same way. So it's better to discuss it with them before installation.
  
BMW Paralever R80R R100R models 1991-1996:
Original tire size: front 110/80-18 and 140/80 – 17 rear

Possible Scrambler tires:
front 110/80-18, rear 140/80-17
Bridgestone     BT 41   M&S
Continental       TKC 80 M&S
Continental        TKC70 M&S
Heidenau         K60      M&S
Michelin           Anakee M&S
Pirelli                MT90    up to 180km/h

Possible Road tires:
front 110/80-18, rear 140/80-17
Bridgestone     BT45
Bridgestone     BT46
Continental      ContiGo
Metzeler          Lasertec



BMW Monolever R80/100 models 1984-1995:
Original tire size: front 90/90-18 and rear 120/90-18

Possible Scrambler tires:
front 110/80-18, rear 140/80-18
Continental        TKC 80 M&S
Heidenau         K 60     M&S
Michelin           Anakee M&S
Pirelli                MT 90   up to 180km/h

Possible Road tires:
front 110/80-18, rear 130/80-18
Bridgestone     BT46
Continental      ContiGo
Metzeler          Lasertec
Michelin           Road Classic
Pirelli                Sport Demon

Alternatively bias-ply tires:
front
Shinko E270      4.00-18
Shinko E-270     4.50-18
rear:
Shinko E270      4.00-18
Shinko E-270     4.50-18

  
BMW Twinshock R80/100 models 1976-1984:
Original tire size: front 3.25-19 and rear 4.00-18

Possible Scrambler tires:
front 110/80-19, rear 120/90-18
Continental        TKC 80 M&S
Heidenau         K 60     M&S
Bridgestone     AX 41   M&S

Possible Road tires:
front 100/90-19, rear 120/90-18
Bridgestone     BT46
Continental      ContiGo
Michelin           Road Classic
Pirelli                Sport Demon

Alternatively bias-ply tires:
front
Shinko E270      4.00-19
rear:
Shinko E270      4.00-18