Question about groove tubes

[halfnote]

O.K. I have read over and over that it is allright to use GT's in my Stiletto as long as they are rated 4-7 I have a set of 7s
Can any one tell me what this means, how if at all it affects tone?
Thanks

 

[crane]

Mesa scale / Groove Tubes scale
Red / 4
Yellow / 4
Green / 5
Gray / 5
Blue / 6
White / 6

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So your grade will probably take the tube to 60% dissipation