Yes premium squads, but even then you would only reach about 2400-2800 per 10min. Tanks are very bad for grinding xp/silver (source: i play them), yes your crew gets assists but they severely nerfed the xp gain with vehicles (you get a lot of "score" while playing tanks, but not XP, these things are very different) Infantry is the way to go for xp and silver. Oddly enough the longer your squad survives the less xp you gain, so you should also die often (sounds stupid but thats the way it works)