I run a 110/80 x 19 front and 150/70 x 17 rear on my 990. Michelin Anakee 2 tyres.
The bike turns in well and grips well. No dramas at all on winding mountain roads or motorways.
In my experience of modifying MX bikes into supermotos a fat tyre can affect turn in and stability.
With the 17/19 combo I just fitted them and rode it. I can take my hands off the bars at any speed and it will slow down all the way to walking pace without shaking it's head.