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© 2003 Brian F. Schreurs
Even we have a disclaimer.

"What those people don't understand," the admonishment goes, "is that they may have four-wheel drive, but all cars have four-wheel brakes."

You can be sure that the speaker and all the people sagely nodding their heads are the same people who spend the rest of the year complaining about SUV safety and fuel economy as compared to whatever vehicle fits their criteria of a "sensible" car. But when winter really hits, and 4WD trucks demonstrate the one thing that they are demonstrably better at, the judgmental peanut gallery falls back on the all-cars-four-brakes schtick as their last bastion of self-righteousness.

Try to argue the point and they'll likely be able to recite the exact number of disabled SUVs they saw that morning -- though they'll be less specific about the number of other disabled vehicles, or what percentage of the vehicles travelling that day were SUVs. The danger of keeping track of the disabled vehicles without also keeping track of the ones that make it through is that doing so makes far too many assumptions: it assumes that there is a roughly even mix of SUVs to cars, so by extention it assumes that if there is a disproportionate number of SUVs on the side of the road then SUVs must be trouble in the snow. In fact, if there is a disproportionately high number of SUVs on the road (as one might expect in snowy weather), then the number of disabled SUVs might be higher than cars even as the percentage of SUVs out of the overall population of travelling vehicles might be considerably lower.

For example, say there are ten vehicles on the highway; it's snowing, so eight of them are 4WD trucks. Three vehicles spin out -- two trucks, and one car. Twice as many trucks spun out as cars, it's true; but this doesn't paint the full picture. Out of all traffic, in this scenario, 75% of the trucks made it through, whereas only 50% of the cars made it through. If you were stuck in this scenario, your chances of making it to work would be much better in a truck.

Never mind that though; people tend to exempt themselves from such statistics because they're all above-average drivers. It doesn't apply to them.

The real danger of the all-cars-four-brakes argument is the stunning ignorance of the forces at work in winter driving if the people who propound it actually believe it themselves. How can they make informed choices to protect themselves in the winter if they really, truly believe that all cars stop equally well -- or poorly?

The first critical flaw of the argument is the notion that all brakes are equal. This is absolute nonsense. Setting aside the thankfully-extinct four-wheel drum brakes, consumers today are still faced with cars that may have either two-disc/two-drum brakes or four-disc brakes; single- or dual-piston calipers; varying diameters and contact areas; vented and non-vented; different pad materials; and antilock or non-antilock systems (or two-wheel antilock, or three-channel antilock...). This plethora of choices not only causes variations in how much overall braking force any given car can generate, but also how much force that car can generate before locking up the brakes. One can be sure that, all else equal, the more advanced braking system is going to drag the vehicle down with greater authority even in unpleasant weather.

Unfortunately, these days consumers seldom have a choice of brake systems on any one model of car, and only the diehard enthusiast seriously considers upgrading the system after leaving the dealer's lot. The only portion of brake performance under consumer control is the replacement pad compound, which people often evaluate based on cost or brake dust rather than stopping ability. Nevertheless, though most won't think about improving the performance of their car's brakes, the vast differences in the quality of original equipment brake systems remain. Some vehicles do stop better than others.

The second, and perhaps more damning, flaw of the all-cars-four-brakes argument is the notion that the brake system is the determining factor of a car's ability to slow down in hazardous weather. The underlying assumption of the argument is that all vehicles have trouble finding traction to stop in hazardous weather; the argument then proposes that the reason is because the brakes are inadequate? Surely not. Tires are the first-line determinant of traction; if the tires can't find enough grip, then even race-grade braking systems will go wanting.

Tire technology is an advanced field; consumers are free to choose from barely-legal $25 gumballs that present a hazard even in a light mist (those four-for-$100 generic specials) all the way out to highly specialized tires designed specifically for extreme dry-weather performance (BFGoodrich g-Force), or extreme snow and ice performance (Bridgestone Blizzak). Most people have little use for high performance tires, so they select a middle-of-the-road "all-season" tire designed more for a long service life than anything else. Such tires are usually decent in normal driving, adequate in the rain, and passable in light snow; those who live in areas that see regular snow accumulation or icy conditions would do well to consider buying a set of dedicated winter tires.

But all this talk of tire selection is entirely out of scope for the all-cars-four-brakes crowd. These people are erroneously focusing on brakes when they ought to be considering what kind of rubber is keeping their car stuck to the road; they ultimately prove to be the greater hazard as they do not truly understand the dynamic environment that their car must perform in. They are not equipped with the knowledge to properly prepare their car for winter driving or to safely control it when winter driving conditions appear. They are no better off than the very SUV drivers they are so quick to bash -- perhaps less so, because they don't even have the benefit of four-wheel-drive when they do "mysteriously" leave the pavement.