That's interesting, since Yamaha calls for a tire with a higher speed rating than that of the ME880, which is only H-rated (130mph). Regardless of how long you will actually spend there, the Vmax is still good for 145mph in stock form, and as such demands a tire that is at least V-rated (149mph), such as the Shinko T230, and the Bridgestone that's factory fitted.
And, guys reading your insurance policy, are you serious? It would take most of a day, if not more, to read all the small print that comes with it!
If in doubt, simply call your insurer. Tell them: I am considering mounting a tire that is a non-standard size not recommended by the manufacturer on my bike, will it affect my policy? And for god's sake, do NOT say you've already done it.
I will put $$ on the answer being 'if you do that your policy is no longer valid'. :confused2: