Although I have an 04 not the later model, have a look at this thread for an idea of size and fit.
I bought mine to fit over the panniers and luggage, so they didn't have to be stored in the tent, so you could go at least one size down for just the bike.
http://www.triumphrat.net/sprint-for...he-1050-a.html
In the thread is a link to one of my albums where I have posted pictures of the cover on.
Hope this helps
Rexx
