Usually between 20 and 25 depending on the make. In situations like this, I just mark the weight I'm adding. That way the weight of the bar doesn't matter. For example, my log entry could look like this:
Skulls - EZ Bar
(1p + 10)e x 12
That means 1 plate (45) and a 10# on EACH side for 12 reps. You can also put 55e. Whatever works. That way, next time you do the exercise, you know what u used. You can use this for any bar in any gym, as long as you write down what actual plates you put on there. This way, whatever the bar weights won't make a diff.