Apart from some limited access highways, speed limits have been relatively unchanged for over 30 years now. The current speed limits were assigned before things like anti-lock brakes and traction control had even been heard of. Roads are safer and cars are safer, but our speed limits haven't kept up. Why is that?

Doggedly adhering to an obsolete set of laws is really no different from obeying those "weird/little-known" laws every state has: it just doesn't make sense. I guarantee you there aren't too many Texans abiding by the "take no more than three sips of beer at a time while standing" law, or people in Alabama consciously abstaining from games of Dominoes on Sundays. Silly, obsolete laws should be neither adhered to nor enforced. Unfortunately, the law enforcement community hasn't figured this simple fact out yet.

So how fast should you drive? That depends on the location and conditions. Rule #1 is to keep pace with traffic when you're driving in traffic. If you're doing 55 in a 55 zone while everyone else is doing 80, you're far more likely to cause an accident than if you were doing 80 too. If there's no traffic around, 10-15mph over the posted speed limit is pretty reasonable, up to a limit of 85 (unless you're on a really long, really straight, really level section of highway). Most street vehicles start becoming unstable around 85mph in the presence of wind, turns, etc.

In residential areas, 35-40 is safe for wider streets while 25 is good for the narrower ones. On curves that have yellow speed advisory signs, doing more than 5-10mph above that number requires a car with very good cornering and good tires. If it's raining, stick to the speed limit or slightly below in curves and only slightly above on other roads; if some other driver does something stupid (which they often do), you'll need the extra room to stop.

In the case of snow, all bets are off. Regular powder snow isn't any worse for traction than rain (sometimes better, even), but if the snow is on top of ice, you're going to wind up in a world of hurt if you speed too much. One really good way to get used to driving in the snow and ice is to find an abandoned parking lot, or a lot at night or after store hours, and practice stops, starts, and turns. A little experience goes a long way on slippery pavement.

Tailgating