Trackicks don't have axle tags.
Yours had 5.12s from the factory.
The only lower gearing options are 5.38s or 5.62s. Or 5.83s, if you can find them....but I think I have only seen 1 set for sale, ever.
Just to clarify, while the 5.38s and 5.62s are somewhat rare to find, there are some that pop up for sale occasionally (I actually have sets of both in the classifieds section now). But the 5.83s are practically impossible to find.