Thanks, Matt. Good post. I can't remember my college phsyics, and my text books were ruined by a leaky roof
; How does area affect friction *after* the tires are skidding?
I've been following this thread closely, and I've got to throw my two cents in because I've held a strong opinion about tire width for a long time, anyway. IMO, wide, low-profile tires are a fad, with no benefits except under the extremes of racing. I first noted them showing up on high-end sports cars and G machines (muscle cars with beefed up suspensions and tires designed for extreme cornering. ie, trying to pull one G on the skid pad). Then on higher end vehicles. And now they have filtered down to OE on nearly every model except the low end economy autos. Whether for perceived traction increases, a pricey look, a sporty look, or just plain better looks, people like them and they're everywhere now.
As fas as safety goes, my experience is that, as Matt pointed out, increasing the patch area distributes the weight over a larger area, reducing the force per area unit (psi, kg/cm2, <your units here>). While a large sticky patch may be desirable for racing and AndrewJ's high-speed turns
under, as diesel_john called it, "ideal conditions", my goal is to get more force between my tire and the pavement for those less-than-ideal conditions. Rain, snow, and mud to be specific. THAT'S when I need traction, not on dry pavement, and a narrow tire gives it to me. Hydroplaning avoidance has already been mentioned, but I also get much better traction in snow with narrow tires.
I have to agree with diesel_john on both of his posts: Some of our practices are not safe. But for normal-driving safety, I believe skinny tires are the way to go. (and the narrow tires' reduced price and increased in FE of are icing on the cake
)