So i guess these dont come with a gas gauge. Any solutions? or check every once in a while!

And is there any tail lights i can upgrade to? or just custom L.E.D. light

 

use your milage to keep tabs on your fuel level. going to a new rear light is not an upgrade, bling never is

 

clear alternatives makes an integrated clear led taillight for $114.95

go to your local dealer and order part #2010-0138

 

Fill the tank, and go riding, taking into account how many miles you can get before having to switch to reserve. Then, consider what kind of riding you did (City, Highway, canyons, hard riding, cruising, etc). It should give you a feeler of the range of a full tank of gas. Then, as you ride more, you should have a pretty good average estimate of how much you can ride before having to fill up depending on the type of riding you do.

Ebay is a nice place to search for tail lights solutions.

 

You should have a reserve light which usually indicates 1 gallon left. I have never seen a non BMW bike have a gas guage.