@pat-lachute, Valhalla will be able to support this precision in a bit. Still, it'd be best if you edit those ways to be described by a handful of nodes. You can have a look at some roundabouts, they often only have the intersection nodes, so it looks more like a diamond than a circle. AFAIK there's no "minimum distance" guideline, but generally I wouldn't be more precise than 1-2 m in between nodes (at least when describing road geometry).