Is short sleeved shirt OK everywhere for men? Are sandals without socks OK for men, too?
Although certain general standards are widely accepted, there has been little interest in narrowly prescribing what constitutes modest dress for Muslim men. The code of dressing in Iran for men is not as rigid as the women, long trousers covering up to ankle, long-sleeved or Short-sleeved shirts and sandals without socks are acceptable. But it prohibits 3/4 trousers and shorts, although you may not be laughed at by the public, the police may warn you and advise to change your dress. It is common for the Iranian guys to wear 3/4 trousers outdoors but of course not in the cities.
Check the cheapest Iran tours.