I rode in Iran and on their Freeways--specifically, the Qom Autobahn-- quite often. You are better off on the Freeways than the side feeder/service roads. The latter have just as much traffic, with truckers and ther vehicles trying to avoid the highway tolls...so you are better off on the well shouldered freeways. Hop over the fence if you need to go into a town or truck stop for food and frolic, they didn't have "rest areas/service areas" that I recall. Iran is a great cycling country: odds are in the towns you'll see other riders and some of the clubs offered me help and said to stay in touch with them about any hassles you might get. I had a couple guys in a car shadowing me for a while so I got the plate number and a car description, and gave it to the cycling locals, who were quite pleasant and ominous in their promises that something would be done about it. I have a page on cycling in Iran on my bicycle tour page, Iran by Bicycle. Fun photos and you will LOVE your bike tour there.