I need to replace the original tyres on my YS since they are scary in the wet. The problem is the tyre sizes. I can not get 100/80-18 tyres from a good brand. Michelin used to produce the city pro but when I emailed them I was told it is out of production with no intention to produce. The only choice left is a different size. 100/90-18 or 110/80-18. The rim and bike can take both sizes but both have an additional 10mm in tyre wall height. What do you suggest?

Myself? I would go with the 100/90 as the width will sit better on the rim matching the original and any height difference if it affects the ride at all can be negated by dropping the forks up through the yolks by 10mm.