If all you are trying to do is get out a mile or two (line of sight), don't worry about SWR, your radio (if factory) is only putting out the legal 4 watts and performance gains will be negligible.
If you have a tuneable antenna (one that you can shorten or elongate), and the antenna is somewher other than the mid-point of your vehicle, then you can grab a SWR meter and tune it in based on it's location on the vehicle - but again, with standard power input/output, your results will be negligible.
To be honest with you, if you're just running a standard radio, it's more hassel than what it's worth - yeah, you'll be able to listen and talk maybe a few more hundred yards, but that's about it.
(If you decide to go hardcore, there are calculations regarding the length of your antenna coax, excess being coiled to reduce or increase SWR, shielded power connections, etc, but for a standard 4 watt rig, it's not worth it.)
As for magnet-mount antennas, I suggest a piece of cheese-cloth or similar material; even 4 watts of transmission power will give you a nice little rust circle if left attached too long.
If you have a tuneable antenna (one that you can shorten or elongate), and the antenna is somewher other than the mid-point of your vehicle, then you can grab a SWR meter and tune it in based on it's location on the vehicle - but again, with standard power input/output, your results will be negligible.
To be honest with you, if you're just running a standard radio, it's more hassel than what it's worth - yeah, you'll be able to listen and talk maybe a few more hundred yards, but that's about it.
(If you decide to go hardcore, there are calculations regarding the length of your antenna coax, excess being coiled to reduce or increase SWR, shielded power connections, etc, but for a standard 4 watt rig, it's not worth it.)
As for magnet-mount antennas, I suggest a piece of cheese-cloth or similar material; even 4 watts of transmission power will give you a nice little rust circle if left attached too long.