Convert your cylinder bore diameter to inches and then multiply it by the given ring gap suggestion.

For example.

Cylinder 2.
86.010mm converts to 3.386"

Top ring gap calculation:
3.386 x 0.0045 = 0.0015237"

You're looking at 15thou which is about right - if you're going to give it death on the track or hit it with gas later on i'd personally make it a little larger.

Make sure the ring faces are still square to each other when they're closed up too.