The Inside Story

It is said that Americans are  obsessed with the idea of speed, an obsession upon which they hold [noble] For this is the jet age. And while some men speed  through space faster than sound, earthbound daredevils attempt to break  new speed barriers with stock cars. Special, highly tuned models of the same passenger cars that are driven by America's new  freewheeling, peripatetic population. Actually, stock car racing is a proving  ground for the auto industry, the torture rack upon which engines, equipment,  and tires are pushed to the limit. How tires respond when driven at high speeds often  means the difference between safety and disaster. You should know more about them. Not just tread design or the rubber content,  but what's on the inside where it counts. In fact, you might call this the inside story. Today, a great deal of our long  distance driving is done on superhighways and turnpikes that permit or  even require traveling at high legal speeds. How well your car handles  depends greatly upon your tires. Traveling at high speeds, tires get hot, building up pressure through constant  flexing and pounding on the road surface. Under some conditions, tires can  heat up to more than 250 degrees. At sustained speeds over 75 miles an hour,  and you shouldn't be going that fast anyway, even some brand new tires are  beyond their capabilities. Sometimes when heat and pressure build and  the tire hits a rock or a chuck hole... Fortunately, this type of  trouble happens less and less as today's tires are safer  and stronger than ever before. But there are other important  factors that affect tire performance. Maybe you never thought about it. Tires have a lot to do with the degree of  control you have over your car at high speed, particularly when pulling out, passing  another car, swinging back into your own lane, or when someone enters a busy  highway from a side lane or feeder road. For safety, you should maintain normal  speed, gauge your distance and timing. Slow-ups cause crack-ups. How well your car reacts to quick  maneuvers depends, in large measure, upon the directional stability of your tires. How many times have you been  in situations like this? Or this? What happens? When you pull out, the wheel  turns the way you want it to go, but the tire on that rim  wants to go straight ahead. How well your tires respond, follow the rims, determines the stability of  your car, the control you have. What's inside the tire, the cord, is  what really determines your control. Unfortunately, most drivers  know very little about tires. For instance, would you believe  that the average passenger car tire is built to take more punishment  of its kind than tires on a racing car? Ever see anyone kick a tire to test it? It really doesn't prove anything, but they'll do it every time. Or how many times do we hear... "What I want on this car is rubber  like the racing drivers use." "Ralph, if I gave you a racing  tire, you wouldn't ride on it." "Why wouldn't I?" "Come with me a minute and I'll show you." "First place, it's too hard." "You know they carry up to 70 pounds of pressure?" "And look here." "No sidewall protection like you get on yours." "You see, Ralph?" "Rubber isn't what gives you all your protection." Rubber gives you traction. "The cord is the backbone of the tire." "It's what's inside that counts." "Man, here's your protection." "You ought to see how a tire is built." At one of the nation's leading  tire testing laboratories is a demonstration unit that shows step  by step the construction of a tire. Tires are built on a drum, around which two or  more layers of cord fabric are wrapped and sealed. This is the heart, the core, the guts of the tire. The wire bead is what grips the rim. The tread and sidewall rubber is  laid over the carcass of the tire. The building drum is collapsed, and the  tire is ready for molding and curing. A sort of pressure cooking operation. And there you have a finished tire. In this case, an exact replica of the  real thing, from carcass cord to tread. Would it surprise you to know that  three out of four new cars rolling off U.S. assembly lines come equipped  with tires made with rayon cord? They're no cheaper. They cost just as much to make  as any other comparable tire. One important reason why car manufacturers insist  on rayon is that it gives you a smoother ride. When rayon-cored tires cool, they won't develop  the flat spots that give you a rough ride. We demonstrated this with cars that  have been sitting out all night. Put water on the hoods, water in a  glass, photograph the difference. This one's on nylon tires. This one's riding on rayon. The vibrating drops of water show  visual evidence of what you feel. Here's an even more convincing demonstration. Here's how one laboratory  makes the flat spot test. Tires are heated by running on a test wheel,  then stopped and allowed to cool under load. Then the wheel is started again. The tire now on the test wheel  is built with nylon cord. As it speeds up, the sound you'll hear  is like a railroad car with a flat wheel. That's what it's like when  a tire develops a flat spot. Look at that lever arm bounce,  just as your car would do. Now listen to the difference when  a rayon cored tire is put on the test wheel and run under the same conditions. Pretty smooth, huh? But even more important, rayon  cord gives you better control when you need it. Ever see a piece of rayon tire cord? Each cord has several strands made  of thousands of tiny filaments. Doesn't look like much to  hang your life on, does it? But this is where the strength  of a rayon cord tire begins, in the strength of each tiny filament. The strands of filaments are  twisted together, then woven into a fabric that forms the backbone,  the framework on which tires are built. You saw how tires are made. Here's how many tires are tested for strength. This is a slow speed plunger. It applies steady, continuing pressure to a given  point on an inflated tire until the casing gives. Unfortunately, this test is nearly meaningless  because this just isn't how a tire ruptures. This slow test doesn't take into consideration the recognized effects of heat and  speed on different cord materials. For this reason, scientists at American Viscose, one of the companies that makes rayon tire cord,  designed and built a high-speed plunger machine. This device records the precise measurements  for braking energy or impact resistance under conditions simulating those  of tires in actual highway use. For instance, a tire is  preheated up to 225 degrees--- as hot as it might get on a  summer day driving at high speed. A three-quarter inch plunger is  fitted into the firing chamber. The weight of the plunger  varies depending on the test. A technician sets the pressure  of the firing chamber. This controls the speed the plunger will travel. He fires. At 15 milliseconds, the plunger  did not penetrate the tire. He reloads, increases the  pressure, and fires again. At 13 milliseconds, about 100 miles an  hour, the plunger ruptures the tire. Comparable nylon and rayon cord  tires that are similar at low speeds react quite differently when  given the high-speed plunger test. At high speed, rayon has superior impact  resistance, higher braking energy, a quality long recognized in U.S. government specifications. On the famous 4,400-foot drag  racing strip at Atco, New Jersey, Rayon and nylon cord tires are given a  series of continuing tests by engineers who measure and compare performances  under actual driving conditions. Let's hear what the engineer in charge has  to say about these unique tests and about the specially equipped test car. My name is Frank Akatowicz. This car has been instrumented to study  its directional stability on the highway. That is, its ability to follow  a course set by the driver. Now, we have instruments to sense the motion of the car and also the movement of the  steering wheel as made by the driver. You'll see on the front fender and the rear fender sensitive accelerometers which measure the  crosswise accelerating movements of the car, that is the tendency of the car to  dart to the right or to the left. Now, going inside the car, we have the 10-turn helipod driven by the brass gear  fastened to the steering wheel. The signal from this helipod, as well as  the signals from the fenders of the car, are displayed on the cathode ray  oscilloscope in the rear of the car. And this oscilloscope is powered from  the electrical system of the car, and both signals are displayed  simultaneously, so that the coordination between what the driver does and  what the car does can be displayed visually. We photograph this visual display with a Polaroid land camera, so that we can get an  immediate picture of what happens. Here are samples of the tests that are being run. One test maneuver is typical of the  sudden turns that must be made when a driver tries to dodge an obstacle  that suddenly appears in his path. The difficulty comes in trying  to re-establish control. Changes in heading can occur much  faster than the driver can correct them. In another test, the driver  flips the wheel and lets go. a dangerous maneuver at high speed. But the rayon cord proves to respond quickly,  brings the car safely back on course. In such circumstances, a forgiving  set of tires can be a great help. The engineers say rayon cord  tires won't prevent accidents, but they do provide a very welcome margin  of safety over nylon, when you need it most. For further proof, we went to the men who  really know how to handle automobiles. The men who race the stock cars. At Charlotte, North Carolina, we brought  in some of the top drivers in the country. Junior Johnson, veteran of  17 years on racing tracks and now building them instead of driving them. One of the great all-time competitors. Richard Petty won the NASCAR Grand  National and Daytona 500 in the same year. Now teamed with his race driver dad, this 30-year-old Carolinian says  racing strictly a business. Cale Yarborough, youngest of the new breed,  entered his first Grand National when he was 17. Now one of the country's best stock car pilots, Cale has his sights set on  winning the Indianapolis 500. Bobby Allison, four-time NASCAR modified chair. He's only 29 and one of the nation's top ten. Bobby has a rare combination of skills. He's a mechanic who builds  them as well as drives them. Under the direction of veteran Jim Curley,  technical director of the American Viscose Rayon Tire Cord Research Program, the  pros agree to help him make a test. Curley lays down the ground rules. Each man will make several runs  over a predetermined course. They'll use one set of tires, then another. At no time will they know when they're  driving on nylon or rayon cord tires. We want to find out what they can tell  us about the handling differences. The drivers themselves helped set up  the test course, using both front and back straightaways of the one and a  half mile Charlotte Motor Speedway. Driving standard Ford, Chrysler, and General  Motors cars at normal highway speeds, between 60 and 75 miles an hour, they  really rolled rubber through those pylons. Now let's follow Bobby Allison. His job is to maneuver that car at  top highway speeds and evaluate how it handles, how it responds when  he changes lanes and cuts corners. When the driver had the feel of one  set of tires, he pulled into the pit where a four-man crew quickly put on a  companion set made with the other cord. At no time did the driver  know what he was riding on. We used twenty different sets  of tires during the test. Ten of rayon, ten of nylon. All right off the shelves of half  a dozen leading tire manufacturers. Bobby's now back on the course and giving  his fresh set of tires the same test. Frankly, we didn't have the slightest  idea what he'd tell us when he finished. Here he comes. Everything is unrehearsed, just as it happened. Jim Curley handles the mic. Well, Bobby, how'd it go? Let's get comfortable. Take that helmet off. OK. You were out with one set of  tires, and you came back in. We changed tires for you. We put companion tires on to the first set. You went back out. We're interested now in your comparison  between these two sets of tires. Well, on the first set of tires, I could make it through the front  course at just about 70 miles an hour. The car had a good bit of yaw. And I couldn't make it through the back course  even down to 60 without knocking over the pylons. And then with the second set of  tires, I could make it through the front course at over 75 miles  an hour, very smooth at 70, and when I slowed down to about 60, I finally  could make it through the back course. How do you find this testing sedans  as compared with station wagons? Well, the station wagons handle a little bit poor, so the conditions show up a lot quicker and  a lot more severe in the station wagons. Fine. Thank you, Bobby. We'll be doing this some more. Well, Bobby seemed quite  impressed with the Rayon tires. Now there's Richard Petty passing the stand. Remember, these champs were chosen not only for  their driving skills, but also for their ability to read right through a car's operation and tell  us what effect tires have on how the car handles. Wow, that was a run. And here we go again. Petty's ready to give it another try. This trip, on another set of treads. The average motorist never gets a chance to make first-hand comparisons like this and then  record his observations right on the spot. In fact, the average driver would be in  serious trouble in some of these situations. Wonder what Richard has to tell Curley. We're interested in your comparison  between the first set of tires you rode on and then the companion  set that you-you just came in on. To my reading, I would say that the the  first set was a little bit the better. They was more stable and down  straightaway and through the corner booth. Any sharp maneuver or anything with the first set, it was one way and with the second set it was  just exactly the opposite and it made it was real bad really and I would say  that we would go with the first set. Here comes Cale Yarborough now. See him whip that car through its paces? Man, this is driving. Cale doesn't know it, but we'll tell you. He's on nylon cord tires this time through. Just watch that car sway as he makes his turn. Here he comes again, this time on Rayon. The way we ran the tests impressed the  boys with our fairness, our insistence that they give us the plain, unvarnished  facts, just as they saw or felt them. Let's listen to Cale as he gives his verdict. Tell us, did you prefer the first set  of tires or the second set of tires? Well, I really preferred the second set of tires. It gave the car a lot of... They were a lot more stable than the first set. The first set had a lot of swaying to them when  you would go in and out of the pylons and well, the second set was just stuck  better all the way around. Okay, here's Junior Johnson  at the wheel of another car. Junior was our skeptic. He did everything we asked, but he wasn't  sure it was going to prove anything. This runs through the pylons. He's on rayon. We switched Junior's tires over to  nylon cord while he stayed in the car. Then, back on the course. 60, 65, 70 miles an hour. He made quite a run. Let's see how he takes them this time. Okay, Junior, only we knew which tires you  were on, rayons and nylons, on that first run. Tell us, did you prefer the  first run or the second run? I preferred the first run because the second  run the car weaved and waved a whole lot. Couldn't get through the pylon as good. They're not near as stable as the first set was. You You had an easier time  with that first set of tires. That's right, I sure did. Here in slow motion is what was happening  to the tires these drivers were testing. This is a nylon cord tire responding  to a turn at 70 miles per hour. See the sidewall bulge as the tire corners? Now, a companion rayon cord  tire makes the same maneuver. Notice the difference? Less bulge, less riding over onto the sidewall. This shows the superior  stability of a rayon cord tire. For three days, we sent our  drivers through the course, first on one set of tires, then on another. For three days, they put cars just like yours  through tests that simulated situations the average motorist might encounter while traveling  at high speeds on turnpikes and expressways. After each run, we called them in, and  recorded their on-the-spot evaluations. Well, I liked the first set  of tires a little better. How did they handle? Well, first set of tires, I  could go through the pylons at a little bit better speed than I  could the second without hitting them. Was the car easier to handle on the straightaway? Well, on the straightaway, both  sets of tires, it was hard to tell. The big difference was in  maneuvering the car in the pylons. That's right. Any Any of the lane changing maneuvers  was where the the difference did show up. Well, there wasn't a whole lot of difference. About the biggest difference I seen was  when we run through these pylons that that the second set of tires, I  didn't knock down quite as many, so I figured they must have been just a little bit  better, but they wasn't a whole lot much better. Well, the first set felt a little more  stable to me than the second set did. The second set waved around a wrap smart  and had a lot of sway in the back end. Did you have to do more  correcting on that second set? Certainly did. The second set required a wrap much  more steering than the first set did. Well, the first set of tires  seemed to give me a lot of sway through the pylons and didn't have  quite as much control of the car. It would slip in a real tight turn and the  second scent seemed to stick tighter in the tight turns and get a lot better bite and just  made the car more stable through the pile lines. You've just heard stock car  racing champions comment on what they learned while driving cars just like yours. They drove on both rayon and  nylon cord tires at highway speed and discovered they had more control,  better stability, a smoother ride on rayon. This confirmed scientific evidence being  gathered on directional stability with a specially instrumented car, and evidence  from the laboratory where high-speed impact tests proved rayon cord tires  have greater rupture resistance than those made with nylon cord at  highway speeds and temperatures. Rayon is truly a modern tire  core, up to date in every respect, even when compared with the newest cord material. Rayon is the one fiber selected  by all American tire makers for use in the revolutionary new radial ply tire. Radials, the tires of the future,  deliver exceptional traction, tread wear, directional stability,  overall driving safety, and these remarkable tiresare built with rayon, the  tire cord of the future and the present. So remember, it's not just rubber or tread  that makes the difference in tire performance. It's what's inside that counts. That's the real inside story.