Great stuff again Paul, thanks very much!
A picture really is worth a thousand words, and I think the second one just might offer some form of explanation. The Avenger on the crane is an early model, as borne out by the earlier US Star on a Roundel, whilst the pics showing treaded tyres are later variants. So, I'm guessing that smooth tyres were used originally, changing later to treaded tyres. Despite my thoughts earlier about friction, or 'skipping', the treaded tyre would fall into line with the 'solid' tail wheel tyre, designed to prevent, or at least minimise, bouncing. A treaded tyre, particularly the block tread as shown, would, by the very nature of it's construction, have a thicker sidewall, and a thicker, more dense tread area, making it stiffer overall. Therefore, this would also help in reducing bounce on landing, and it might be that the tread also reduced the possibility of skidding on a wet deck. Might not be the actual reasons for fitting treaded tyres, but it seems convincing enough to me!
Jan, the only shots of FAA Avengers on the ground/deck that I've seen aren't clear enough to show the tyres in detail, but I'll go with the treaded option. It may be that the 'smooth' tyres in the kit are intended for the FAA 'Tarpon I' version, which, although the decals are included, couldn't be modelled OOB, as the cowling lacks the gun trough, and the wings have the .50 cal ports and case/link ejector slots. (I found them after opening my eyes and looking closely!)
BTW, that aint a 'window' in the back of the pic, it's an open sponson deck gangway, with the ship's rail visible.
Thanks again Paul, and I'll have a think about the bomb-bay tank, although it'll be the smaller one if I go for it, as th big one must be a ferry tank, taking up virtually the whole bay, interfering with the bomb racks.