Not 11", +11.
The specified sizes from RS-Watanabe for the DR30 are as follows (wheel type, size, offset):
F: F8 15-70+21
R: F8S 15-70+15
Based on that info, you should be right, or VERY close to right....
I'll be running 16x7.0" & 16x7.5" F8's on my DR30 when I can affor tyres....