Okay so I knocked up a quick photo edit to help you.
Stock 160/60/17
I don't advise doing this, but theoretically the max width possible without touching the chain is 190/50/17
Personally I don't think it's worth the extra millimetres. I don't think anyone will ever stop and say, "Hey those marginally wider tyres look slightly better than average."
If you're gonna do it, do it properly.
You will need to change or mod the swing arm. Fit a new wheel and space out the front sprocket to match the rear. Custom the rear fender and ultimately figure out a way to keep it all compliant if you want to ride within the road rules.
Malaysia, Thailand and Philippines have been doing the wildest mods to this bike since it was first released.