Probably your best bet in traffic is some low NRR ear filters that would bring the traffic noise down to a safe level without blocking what you need to hear. Be sure to choose a color that won't be really noticeable to police, since it's illegal in most jurisdictions to block your hearing while operating a vehicle. One high NRR earplug would probably help in suburban settings, but in urban traffic, you're likely getting as much reflected noise from the sidewalk side as you are from the street side.

Do you play an amplified instrument, record your music, or belong to a band that uses amplification? If not, what would you be feeding in through custom earplugs? If you're just using them for protection rather than a conduit for an audio feed, unless your ear canals are extremely sensitive to pressure, there's really no reason to get custom fitted earplugs. Plus, since custom earplugs do their job by blocking the opening rather than sealing the ear canal, they're prone to actually carrying noise into your ear when they touch your helmet, your hair, anything the cord touches if they're corded, or your pillow if you're wearing them to sleep.

Also, if you're taking any medications (prescription, OTC or herbal), tinnitus is a frequent side effect. Sometimes it is reversible when you discontinue the medication. I recently developed tinnitus, and I'm pretty sure it's because of being switched to a generic form of a med I'd been taking without problems for years. (My third day off it today, and the tinnitus is abating some - keeping fingers crossed.)