What is the wire for?

 

looks to be a wire for a ground.

 

It needs a ground?

 

iirc the antenna needs to be grounded and mounted like that it isn't going to be grounded well at all, so that would make the most sense to me.

 

So ground that wire correct

 

yes it is a ground wire. Antenna's need to have a ground in order to work properly. If not you will have a high SWR, and your cb will not work very good and you run the risk of damaging it. Sometimes you have to also put a ground wire on the mount as well. In order to properly check the antenna you need an "SWR" meter. They cost about $25.

I have used similar antenna's and have checked SWR with the ground wire hooked up and unhooked. In most cases it did help with the reflection, but sometimes it hardly helped at all. In many cases just having a good ground on your mount will do. It really depends on the vehicle, Every set up is different. From what your picture showed it looks like you are mounting the antenna on an ungrounded surface. I would suggest grounding the mount.