Wheel diameter of KWA Lowmac bogie plant carrier (CAIB / VTG)?

[Dungrange]

Does anyone know what the diameter of the wheels on a KWA lowmac bogie plant carrier are?

 

Having just purchased an S-Kits multimedia kit for the CAIB / VTG  KWA Bogie plant wagon, I now need to order wheels before I can start assembly, hence the above question.  The instructions state "if you have sharp curves, 10.5 mm diameter wheels are recommended, wheel pack WP7, instead of WP3, 12 mm diameter wheels."  Since I don't have particularly sharp curves, I'm in favor of going with 12mm wheels if the prototype dimension is around 3' or whatever the metric equivalent that is used now.

[The Bigbee Line]

I think they are a 920mm wheel, 870mm last turn, 860mm scrap

[Dungrange]

Thanks - it looks like 12 mm wheels must be the most appropriate wheels to buy.  I'm guessing that the flanges on 12 mm wheels must foul part of the body on tight curves, hence the reference to 10.5 mm wheels, which obviously allows sufficient clearance.