"If I am rude, I will apologize to you"

You seem very interested in different sentences that are slight variations of each other!  :)

"If I am rude, I will apologize to you"

This is a first conditional sentence, the meaning of which is that you (the speaker) might be rude in the future, and then after your rudeness, you will apologize to the other person.  So both the 'if clause' and the 'main clause' refer to future events.

If you want to shift things back, so that either the 'if clause' or both clauses refer to the present, here are the possible sentences:

the 'if clause' is in the present, but the main clause is in the future: If I am being rude, I will apologize to you. Meaning: if you think I'm being rude now, I will apologize in the (near) future.

both the 'if clause' and the main clause are in the present:  If I am being rude, I apologize.  Meaning: You think I am being rude, so, even before you confirm it (once again), or even if I disagree, I am apologizing now . (very common for apologies, especially those that are half-hearted -- for example, apologies that politicians make - the meaning often being, 'I don't think I am being rude, but if you think I am, then I apologize')  

I hope this helps.

Shawn

It is open Condition.

It is possible.

It is about future happenings.