Sorry Trev. I have been away from the British N-scale scene for too long and should have realised that traction tyres are probably still not commonplace on British locos. However, Mainland European N-scale locos manufactured by the German, Austrian and Far Eastern manufacturers are generally fitted with traction tyres. I am sure that you have probably guessed what I am talking about but just to be sure I have attached a photo of one of my locos. The loco is about the same weight as a Graham Farish 47 but because of the tyres it can haul at least 8 passenger coaches up my 1 in 36 gradients
traction_tyres copy.jpg
The tyres are replaceable but in normal use they last for years. Despite usually having one tyre on each bogie they do not affect current collection as all the other wheels have pickups and even the wheels with tyres can still collect current from their flanges.
John.