There are a number of road classifications in France, the main ones being: A (autoroutes, often with tolls payable), N - sometimes RN (national roads, maintained by the French Government), D - sometimes RD (departmental roads, maintained by individual Departments), and C, maintained by communes. There are also ( although I can't find out what it means) R roads. Rurale? Rough? or maybe Ahhhhhhh - I'd forgotten about them...
This walk is mainly on R roads around Preuilly, but you start at the Mairie and head north along rue du Chaumont Patin, which beomes rue Notre Dame and then Route de Loches. Already it sounds a long way, but all this happens within the first 500 feet or so. Once you are at the bottom of the Chateau you turn along Chemin de la Garenne and things start to get rural. There are potagers on the left and the trees that surround the chateau to your right. Just before the chemin rejoins the main road there is a track on your right, boldly proclaiming itself to be R22
If you take this road (the other sign points toward "la Folie") you come across Route 7. Although it may not look like it, this is a crossroads. Taking a right turn here will lead you back to the chateau, but here we turned left.
These roads look abandoned and uncared for, but someone has been doing roadworks on Route 7, as evidenced by the following photo
A bit further along (It's difficult to judge these things - this is a 1½ mile walk that took us over an hour) you reach another intersection. Althought there are no signs to this effect, the new road is Route 8. Turn right here, looking out for traffic, naturally.
Standing on Route 8, looking towards Route 7Follow this road and you eventually find the Route 8 sign. One hundred metres further along, and you're back in Preuilly.
I have done a mashup map type thing here (in blue), just in case you're ever in the area and looking to stroll.