A tweet is the start of a conversation – or a response to it.
Twitter’s character limit is 140.
When we utilise all 140 characters what we’re doing is not allowing our readers to respond in any way. Not without the unhappy task of shortening, deleting or getting rid of the verbiage we’ve put in their way.
Most will not carry on the conversation. They would if we’d let them get a word in.
The way to do that is to limit character utilisation in your tweets. I would keep tweets to a maximum of 70 to 80 characters. This infographic I found suggests it’s ok to go to 120 however.
Whatever the ideal character count is (and the answer may lie somewhere in between), what’s really key is to ensure you give your audience a chance to say thing as well.