Ok but the numbers don't seem to add up then if the tail is the limiting factor:
GO139: 250x80 tail: 52.7 range: 5.0-9.0
I.S 135: 228-80-54.8 6.5-10
Carve 144: 256 -78 -52.1 5.8-9.5
So far: bigger tail, bigger range, no difference in width so the limiting factor seems lenght and tailwidth, we know it's not length 'cause thats mainly a factor for windrange upwards, speed and swiftness in turns. The only exception is the C144 which is longer, less wide and had a slightly smaller tail.
2008: two years of research, two years of numerous titles etc etc, here are the figures:
GO 144: 248-77.5-52.1 range: 5.5-10
GO 133: 245 -76.0-50.0 range: 5.0-9.5
Futura 144: 248-77.5-52.1 6.5-10
I.S 144: 225-85-58 7.0-11
What do we see? Tailwidth is reduced on the freeride boards, only the IS gets a much wider tail and by consequence a much bigger range but for the other 3 the idea bigger tail = bigger range doesn't quite ass up. What we do see overall for the freerides: less long, less wide, bigger volume, bigger range.
Have we our answer yet?
ps: James if you'll borrow your 10mē rig i'll gradly test it for you