IMHO, it all boils down to how much you think you and your family's safety is worth. In my case, no amount of savings is worth rearending a semi (or having to swerve into an adjacent traffic lane unexpectedly), a real possibility when you consider the speed you are travelling as well as reaction and stopping times.

I personally have seen firsthand the effects of tire shredding as well as the ability of a semi to drive over road debris that would be a real problem to a normal vehicle. Unexpectedly having a mattress fly off the vehicle in front of you while driving on the Interstate in the middle of Chicago is enough to convince me to keep a safe distance, even a little more.

T'aint worth it (to me). Of course this is from an older driver (60), one who finally realizes they are mortal. When I was 20 and 30, driving 50K per year, I thought I could handle anything thrown at me, the same as several of my close friends who are now dead and/or disfigured from traffic accidents.

Guess it's time to get off my soapbox........