antenna is too short adjust the tip out a little and recheck. try and split the middle between channel 1 & 40 for the swr

 

I would advise against that mounting location. Enclosed is a picture, ( though hard to make out what it is ) of my tire carrier where I had my antenna mounted for about 2 months. Never did get good reception there.
The reaction between the mild steel I used, and the cast of the tire carrier, ate away at the cast to this result. To see it in real life, you would see that it ate a good 1/16 metal away in that short time. This is my personal experience and who knows, maybe your steel is better than mine
I opted to drill 2 holes under my license plate holder ( in my 08)arg,,,and mount it there on a aluminum bracket. Get a couple miles reception now.
Passenger edge on the top of pic
Excuse the snow

 

Hmmmm, I ran a ground strap fom my tailgate to the bodytub. Lenghthened my firestick a little and am getting 1.2 at ch 1 , 1 at 20 , and 1.2 at ch 40. I'm picking up clear signals from truckers 15-20 miles away judging from the exits and radio checks I've done. The carrier has me interested though, doesn't a couple manufacturers make the ant mount for the carrier? Were you using one of those mounts. Do you think road salt could have contributed to the corrosion where it was mounted?

 

Oh, I used zinc plated flat bar steel for my mount.