130 is the width, 130mm across the tread. If you go bigger you need to measure the swing arm clearance etc. If you go narrower you have a smaller higher loaded contact patch, so less dry grip and maybe more ability to shift snow.
70 is the % of the width they used to set the distance from the rim to the road, the wall depth or profile. 70% of 130mm is 91mm, 80% is 104mm. Going lower profile the gearing will be off by 2pi of the difference, this is naff all. Your pillions bum will be 7mm nearer the road which Rossi might notice but I bet you or I won't.
17 inch is the rim size, but you knew that.
Heidenau do nice winter rubber in 130/80, it's the same size as the Bonneville.
Andy