Reims is a city in Champagne-Ardenne, France, east of Paris.
Towards all directions
The three-, later two-lane road passing right in front of the train station (Gare SNCF) called Boulevard Louis Roederer leads directly onto A4 in both directions: Paris in the east, Metz/Strasbourg/Germany in the west. Heading down towards the motorway there is a traffic light switching very frequently, where Rue Bir Hakeim comes in from the lefthand side. Almost every car leaving Reims comes along here, so there is a very high density of cars passing by and stopping at the red light. You cannot directly ask people, but with a sign and a charming smile, there is a good chance of getting picked up
Going west (Paris)
The place is the highway ramp going on the A 4 towards the west, at the exit number 22 called Tinqueux. First you will need to get to Tinqueux, a suburb of Reims. Best is to take bus no. 8 towards Thillois and get off at the stop called Millésime, the first stop after the bus passes above the highway. (For timetables and other ways to get there, you can check the website of Citura, the local public transport company.) From the stop it is about 600 m of walking. Start walking back to where the bus came from, out of the shopping zone on rue des Ormisseaux, back to the big road. You arrive to a huge roundabout. From here, turn right and follow the blue signs to A4, Paris until the next roundabout, from where the ramp goes on the highway. There is a lot of traffic and no pedestrian sideways, so be careful to cross the road and the roundabout. On the ramp, there is a nice spot to stop for the cars.
Going east (Metz, Strasbourg, Lyon, Germany)
Get a bus or a lift to the ‘voie verte’ which is near some industrial zones in the Eastern part of the city. Here, it takes about 15 minutes to walk up the ‘l’auoroute de l’est’ A 4 for the toll booth (peage). Be careful to walk on the grass behind the motorway barrier. At the toll booth, I waited 10 minutes for a lift. I kept asking drivers that were stopping where they were going with my voice and sign. Ask for the service station not far before the junction between A 4 and A 26. Good luck/ Bonne Chance!
Buses B and S across town to Cormontreuil (1 ticket, 1.20 euros) but the drop off point was still quite a way from the peage mentioned above, bus T might bring you a bit closer but you'll still have up to half an hour to walk.
Nomadwiki & Trashwiki
Check Nomadwiki for info on accommodation, showers etc. or Trashwiki for dumpsters...and share your wisdom :)