The trip will also take them to Kazakhstan, Uzbekistan, parts of eastern Europe and there will also be a week-long stay with horse herdsmen in Mongolia.
They need prepare for several situations and have packed spare wheels, lights, wiper blades and tools.
"You've got to be able to maintain your vehicle along the way," Mr Brown said.
"There'll be at least one oil change along the way, in the middle of god-knows-where."
The trip takes in the dangerous Pamir Highway. "It's been used for 2500 years."
Mrs Brown said it would be exciting to go through all the countries on the list. "And going in a group means we'll have the support of each other. We're prepared for snow as well as summer."
The couple's Nissan Pathfinder will be put on a boat this week and they will fly out to Russian at the end of April to begin the marathon off-road drive.