Im sorry to ask again. I was browsing through web and found quite a few sites with rim/tyre charts. Here is one:

http://kawtriple.com/mraxl/tire_rim.htm#BT45chart

As you see, black wall radial has 120/70/R17 with acceptable rim 2.75
So, there should be no problems with 110/70/R17 and 2.75 rim?

Look at this example as well:

http://www.dunlopmotorcycle.com/tire...tire.asp?id=92

As you can see, 2.75 is not listed as recommended rim size for 110/70/R17, BUT NEITHER is 4.25 for 160/60/R17 and all of us is using it, as it is recommended by Yamaha.

This is quite confusing to me.