which route are you planning? and when are you planning to be there?
the west is still out for now.
from Egypt, there's 600km of soft sand and sandy tracks, but you could take the train while your wife rides ;-)
the rest of the way, you can go on tar except for a section to Ethiopia that would be tough in the wet season.
from CAR, check www.mobilemedics.org.uk
from "west to east possible again". it sounds hard going and 35 litres may not give you the necessary range.
good luck. its a great country. I loved the people I met.
[This message has been edited by RichLees (edited 16 May 2004).]