Well, if you have a 2-way VHF radio then you are a Ham, so you know there are a lot of things that can cause static in a vehicle. My first thing would be to try some power line chokes or filters. Run the radio power straight to the battery and the ground to the frame, and also ground the radio chassis. Second would be to install the anti-static stuff in the tires, as radial tires can also cause this. Generally it is caused by poor grounding, so it could be that adding more grounds to the vehicle might be the only way to go. I had a lot of trouble with that in big trucks, with the steering tires. Trial and error, eh?