You will seldom see dual color LEDs used in this fashion. You need to use specific wavelengths and rather bright LEDs in order ot make yourself visible. The type commonly used are Philips/Agilent Lumiled Superflux for the "red" portion (actually the official color is called red-orange, as red is a deep red which causes them to not be nearly as noticeable as a taillight). The part numbers are HPWT-xH0x with some common examples being HPWT-DH0x and HPWT-BH0x. They aren't cheap but they are well known to work properly.
As for the amber, the part numbers are typically HPWT-xL00
http://www.ebay.com/itm/60PC-LOT-HPWT-ML00-SUPERFLEX-AMBER-LED-/400445697089?pt=LH_DefaultDomain_0&hash=item5d3c6c6c41 Also, chinese superflux knock-offs are NOT up to the task for this job. They don't have near the legal brightness, the color accuracy nor the lifetimes. I've known people who accidentally ran the genuine superflux at 100mA for several months and they were fine (recommended is 50mA, max is listed at 75mA). The chinese knock-offs often can barely handle their rated current, let alone the max listed or god-forbid over current.