There are two schools of thought on this:
Some say "disclose everything", even if it's outside of the time/fine window. The argument here is that it demonstrates you're trustworthy, not trying to hide anything, and "going the extra mile" to show that you aren't hiding anything.
The other philosophy is to just disclose only what is explicitly asked for in the process. If a form like the SF-86, or online forms such as NASIS/e-QIP, say you don't need to disclose traffic violations over $300, then don't disclose them...now, if your investigator
asks you if there's anything else other than what you've listed, then you can mention it.
I don't have an opinion which of these strategies is necessarily "better"; the latter is certainly legal and honest. The former is apparently favored by those who prefer unfettered openness. In either case, don't worry about having some negative items like that. The adjudicative process is very methodical -- they're not going to hold it against you if you have traffic violations in your past; everyone has something negative at some point or another. They
will hold it against you if you lie about something. The key is recognizing bad behavior, taking responsibility, not repeating past errors, the passage of time, etc.
You can see
Adjudicative Guidelines for Determining Eligibility for Access to Classified Information (February 3, 2006) for the guidelines that are used.
I'm sure others will have other thoughts/opinions on this process, but that's my two cents.