[Graham]

Another Ferrari Fly body model with Amato Chassis, different motor, this time a in line Sideways 20k motor. 

That had me scratching my head for a minute, Sideways only do a 17k and 21.5k motor .... but if its from a Sideways group 5 that makes sense, as its  a re-wrapped Slot It 20.5k Flat 6 motor 

I would take the overall tyre width as measurement personally - all tyres will need a rounding on the edge for consistent performance IMO.
Using a 13mm wide tyre and rounding it so the contact area is 12mm does not make it a 12mm tyre  .... just my tuppence worth 

I am enjoying all the pre race build up and introductions, as usual great work, many thanks to you for taking the time 

Logically speaking, you are of course correct so I have accepted that I made an error of judgement and amended the Scrutineer report above for Class B cars, and we will use the conventional understanding for Tyre widths. So penalties may apply at the end of the series to the non compliant cars in the class (including my own)