Never tried the spare wheel mount my self but I have heard of people go down that route, the SWR should easily be tuned out anyway. The ideal place to mount an aerial be it magmount or fixed is in the dead centre of the body work so mounting at the back you will get a lobe of better transmission towards the front but in all fairness for very local working shouldn't cause much of a problem. The same will go for where my aerial is mounted at the back of the roof rails but it really hasn't caused me any problems that I have noticed. I have used a mag mount and had two problems, went to a high school open evening. The school had pulled back the wire mesh fence around a tennis court and with it being dark I didn't notice the wire across the top which pulled the aerial off and it swung down and scratched the body work. I also knocked it off with a low branch and dragged it through the mud, well the wife wouldn't get out in the mud to pick it up what can I say.
About a month ago I had been out for the day and was tired out after the drive home and forgot the aerial was still on. Just reversed straight under the car port, oops. The mounting and the rail were fine but the aerial was a bit bent, soon straightened out though. On the whole I do feel the roof rail mounting is better for me but may not be right for others.
I'm no expert on CB aerials but I guess the model that HB has mentioned may very well be a good type as I'm guessing from the name it has some kind of spring to give it a certain amount of flexibility. I also have a small magmount aerial for ham bands that is extremely floppy and only cost a tenner so guess what I'll use when I go green laning.
What ever aerial you use and where ever you mount it we have to remember the height and some times we have to make a compromise or two.
Sorry for being long winded.
Jim T
