Actually, the ratio number is just that... It's the ratio of height compared to the tire width.
180 * .60 = 108mm in tire height
180 * .65 = 117mm in tire height
The difference is 9mm or around .4"
Either way... Nothing to worry about and most of us prefer the 180/65 tire and many specifically prefer the Michelin Commander tire. The 9mm difference actually corrects the speedometer error. If you use a separate GPS which displays your speed, it will match up exactly if you get these tires.
The Michelin Commander 2 vs 3... I ordered a set of 3s about a month ago. The rear tire came in within a week and we're still waiting on the front. I've checked other parts sites and can't seem to find any in stock either. According to my dealer, he can see the stock of the distributer here and it shows they have them in stock. Don't know why we don't have it yet though.