I'm not sure if the new bikes have this, but the older models had part of the wiring harness running along the top underside of the rear fender...OK, I just went out and verified that there is indeed a part of the wiring harness running under the fender on my '11 SERGU. I can't get my arm far enough in there to feel the very top part of the fender, but I'd bet it's there. Another member here rubbed that harness due to it coming loose and making contact with the rear tire. I would bet your tire is rubbing on the wiring harness cover, and if so, you'll never see any mark on the tire because the harness cover is vinyl/plastic. But, if you continue, you'll know it soon enough when things start to short out from rubbing the insulation off the wiring.
It is my opinion, and take it for whatever you deem it's worth, that one should NEVER lower the rear suspension to that extent, particularly with one of the aftermarket kits that move the placement of the rear shocks down below the stock mounting hole. There is a finite amount of space for the swingarm to move in an upward direction. Putting 12" shocks in the stock mounting holes is one thing, as you reduce the travel of the shock by 1", and the shock will bottom out before making contact with the fender, but when you move the lower mounting position below or behind/below the stock hole, you've screwed the pooch and are asking for problems. Not to mention that you've changed the geometry of the bike's handling pretty dramatically. And, for $159, you can't possibly have much of a shock, whether they are air or whatever. You can probably pump them full of air and make them not bottom out, but the ride will likely suck big time.
If you are lowering the bike because you are vertically challenged, like me, I would suggest you look into other ways of doing so, but it ain't going to be $159 fix. One option is a fully adjustable air ride suspension, like Legend Air, Arnott, etc. Another is an aftermarket kit that lowers the seat height by replacing parts of the frame support for the seat (an even more expesive solution than adjustable air shocks). I can drop the rear of my SERGU 3" when I need to do so for parking the bike, etc, but I NEVER ride with it lowered all the way down, even though the tire can't hit the fender because the shock won't allow it to do so...it'll bottom out first. I have Legend Air Ride rear shocks...13" version.
Sometimes you get exactly what you pay for...with all due respect.