Answering "yes" will raise a red flag. The adjudication officer at
the oath ceremony will probably ask you to write the date and nature
of the violation on your N-445. When you hand in the form to the
officer, you will probably be asked more specifics about the
violation. The officer has some discretion in allowing you to proceed
to the oath ceremony. Normally, traffic violations by themselves do
not exclude someone from an oath ceremony. Of course, it depends on
the violation and how you handled the violation. DUIs and
hit-and-runs are probably an automatic exclusion. Speeding tickets,
on the other hand, are not as long as you paid the fine or went to
traffic school. Some violations, like not stopping for a school bus
or aggressive driving, may exclude you from the oath ceremony while
the officer does further investigation and evaluation.
With most traffic violations, the adjudication officer is evaluating
your "good moral character." If the violation is not too serious and
you took care of it in a reasonable and responsible manner, then you
should have no problems. However, if it is very serious violation or
you haven't brought the violation to closure (i.e. paid the fine, when
to court, or attended traffic school) by the time of the oath
ceremony, then the officer may want to further investigate the
violation and your handling of it before allowing you to be
naturalized.
If you lie about the violation and the BCIS finds out about later, you
could be stripped of your citizenship and deported. If the violation
is not too serious, I recommend taking care of the ticket before the
oath ceremony. Bring with you proof that you either went to court,
paid the fine, or went to traffic school. If it is a more serious
offence, talk to an immigration lawyer first and explore your options,
including bringing him or her with you to the oath ceremony to help
clear up the matter.