One of the more fun aspects of a driver’s education event at a race track is that you get to use all of the road. Most corners are negotiated by starting at the outer edge of the road, cutting across to the inside edge at the apex of the corner and finishing by accelerating to the outer edge of the road. Since this is not how we learn to drive on a public road it is the first instinct we fight when we drive on a race track. The one thing unique to a race track is that most tracks have curbing to discourage exceeding the width of the track. This curbing can take many different shapes from tall curbing, embedded bumps, or just flat extensions of pavement. In most cases there is no advantage to driving across any of this curbing, but there are always exceptions. In many cases the edges of the track are rutted and dusty because racers routinely exceed the track width and purposely use the dirt. One of my friends who raced Formula V said it was common to hook the inside wheels in these dirt ruts for extra cornering thrust.
Watching professional racing today it is common to see how drivers routinely exceed the track limits to reshape the design of the corner radius to maximize cornering speeds. Even with threats of time penalties, it is a recurring practice that just seems to be growing. But that brings up a related point that going off track can bring mechanical consequences. Quite frequently exceeding track limits and using curbing can damage tires, wheels and sometimes suspension pieces. In severe cases going across curbing can cause the bottom of the car to contact curbing and do damage to floors or other low hanging mechanical pieces. The next time you walk the race track it would be good to watch for scrapes and gouges as indicators of where you should keep all four tires on the track pavement and off the curbing. At Waterford Hills and some other tracks they employ a wave shaped curbing designed to thrust the errant tire away from the curbing. Sometimes the force is severe enough to pitch the car out of control and cause a spin out or worse. Even with that threat it is common for racers to still use the lower parts of that curbing to help turn the car or stop a slide. The risk vs. reward tradeoff is routinely tested when it comes to racing drivers.
It should be very obvious when it comes to driving your own car on a race track that running over curbing doesn’t pay. The potential for car damage is too high and the reward of shaving off very small amounts of time is not worth the risks involved. Most instructors will tell beginning students to leave margins of several inches from the edge of the track surface. It takes quite a bit of experience to know when the tires are on the edge of the track. In addition the small imperfections in track surface will cause the car to move about the track surface. Dropping a wheel off the track surface will have an immediate effect of upsetting the balance of the car often resulting in the whole car leaving the track surface. This is especially true of hard braking.
Bobby Rahal used to be part owner of Track Time Driving School where I instructed for over twenty years. He would give little training talks to the instructors about driving techniques he wanted us all to teach. He had a unique approach to cornering that he developed in his racing career. He would set the car up for hard braking several inches off the edge of the track. As he released the brake he would give a sharp tug on the steering wheel toward the edge of the track before he would give an equally sharp tug toward the apex. As he described it, the braking off the edge allowed for some movement of the car as the tires fought for grip. The movement of the steering wheel would take the slack out of the suspension and the flex out of the tire sidewall which would give a crisper turn in response to the car. Bobby had a very strong respect for track limits which may have contributed to his reputation for not breaking his race cars. To finish first you must first finish.
So not to lose interest of my exclusive road driving friends, there is equal importance to minding not just edges of the road but lane markings in general. Needless to say not all lane widths are identical. This can be especially true of two lane side roads. Plenty of roads do not have painted lines or even center lines to help the driver judge the limits of the pavement. Never assume that even when lines are present the road is a standard width or that you can drive to the edge of the pavement. The outside edge of any road quite often will contain broken pavement rendering the width of the lane less than what might be assumed. Running a tire on the edge of broken pavement is a serious risk to damage a tire or even a wheel rim. I have seen many single vehicle accidents caused by a car dropping a wheel off the edge of the pavement. While it might be tempting to straighten out a corner by cutting across the center line of a road be aware that the car in the opposing lane very often drifts toward the center line also.
A skilled driver will use all of the road available to him, but that skill and good judgment includes maintaining a healthy respect for curbs and edges of the pavement.