Yeh - we need to understand 100%'s policy on how much stuff they will transport for you. Tracksense seemed quite hard initially on how little you were allowed to take, but in reality you could take a hell of a lot more - as long as the extra kit fitted within the boundaries of the semi-cage that each bike went in (it was'nt an enclosed cage, but a kinda cage they could use to forklift the bikes around with).
We managed to get leathers, tools, tyres, boots etc in there, and took helmets as hand-luggage on the plane. They don't approve of taking fuel though!!!
With the CSS they were far more tolerant of taking lots of stuff - probably because their transporter wasn't full up??
I'm rambling again, but in short - take as many tyres as you can get away with!!
Tim