There was a time in America when all tires were of four-ply bias architecture and of the same 90-series aspect ratio using rayon cords as reinforcing material.
These tires were mounted on steel wheels of rim width dimensions representing about 70 percent of the inflated tire cross-section width.
Back then, only three wheel diameters were used for original equipment passenger car application13, 14 and 15 inches. Light trucks used 15-, 16- and 16.5-inch diameter wheels, and all of them used hub caps. As for tire inflation, 24 psi was the pressure universally used.
These were, of course, the days prior to the advent of National Highway Traffic Safety Administration (NHTSA) regulations, which, in my view, the U.S. automobile and tire industries brought upon themselves.
Life was simple before that time. For example, consumers were free to replace their worn-out OE tires with tires of larger cross-sectional inflated dimensions, hence increasing tire load reserve, durability and treadwear resistance, while still maintaining the originally established tire inflation pressure of 24 psi. U.S. vehicle manufacturers at that time routinely fitted OE tires to their vehicles of the smallest possible dimensions they could get away with, in order to save themselves money.
I vividly recall the question vehicle manufacturers used to ask their tire suppliers: How much overload can your tires take? Tire loads, sizes, inflation pressures and wheel sizes then, as today, were established by U.S. vehicle, tire and wheel manufacturers after having consulted the Tire & Rim Association book published by the tire and wheel producers through their marketing and sales organizations, but this only as guidelines.
Fundamentally, tire types, sizes, loads and inflation pressures then, as today, are determined from comprehensive studies of tire thermo-mechanical stresses, and according to the type of tire architecture used, the materials tires are manufactured from, the level of precision and uniformity achieved by the tire and/or wheel manufacturing processes, the type of vehicle the tires are to operate on, and under what conditions.
By now one could conclude that a pneumatic tire is quite a concentrate of technologies and a complex system not for the faint of heart. The key word here is SYSTEM. Incidentally, I introduced the road/tire/vehicle/driver system concept at Ford Motor Co. in the early 1960s. The program included evaluating the vehicle evaluators, which was quite a controversial proposition back then.
In the early 1960s, under the pressures exerted by U.S. vehicle producers to reduce OE bias tire prices, the tire producers made, in my view, a serious marketing error: they reduced the number of plies to two from four in order to meet price-reduction demands. Such action, however, had serious negative economic as well as performance consequences, for consumers quickly noticed the lower treadwear and puncture resistance of these two-ply bias tires.
Tire retreadability, then a common practice in North America and elsewhere, was also greatly reduced. These two-ply bias tires delivered about 18,000 miles of service, if that. This is what develops when money becomes the main preoccupation, and in our case, interferes with serious road/tire/vehicle/driver system development.
I was horrified and expressed my dissatisfaction to my superiors at Ford, but to no avail. In fact, I was told to leave tires alone, that tires were strictly the domain of the tire suppliers. How wrong can one be. I predicted that if such trends would persist, it would not only bring in U.S. government regulations, but would also mark the beginning of the demise of the U.S. tire industry as we knew it at the time.
Sure enough, this is what eventually happened, and it did not take long, for when the U.S. bias-ply tire makers had to radialize rapidly to compete with Group Michelin, they simply could not, essentially because of insufficient or total lack of know-how in radial-ply tire design, development, and, of critical importance, manufacturing know-how and road/tire/vehicle system tuning.
There was also the always critical question of the money required to radialize their plants correctly. In this regard I recall a conversation I had with Francois Michelin following his visit with Henry Ford IIand later on with a group of Ford engineers at the Ford product development center, including myselfwhen I asked him: Why, in your opinion, are the U.S. tire manufacturers so reluctant to radialize?
Without hesitation Mr. Michelin replied, Money, to which I countered, Mr. Michelin, even with money, without acquiring the correct technological know how, you could waste lots of it, if not all of it.
Incidentally, by the late 1960s, most tire manufacturers throughout the world already had acquired licenses from Michelin for the right to produce and sell Michelin's patent-based steel cord-belted radial tires for a variety of vehicle applications. However, these licenses did not include Michelin's technological know-how, which was considered absolutely necessary to produce such tires correctly.
Keep in mind that, even when Michelin was producing only bias tires, the firm was well known already for its high manufacturing precision and uniformity. With radial tires, even higher manufacturing precision and uniformity is required for the tires to perform smoothly and reliablyand this for twice the mileage of bias tires.
On the other hand, and in a sort of Catch 22 situation, Michelin had to learn how to market their radial tires in America, a market they knew little about at the time. Even with Michelin's managing in 1965/66 to get a contract with Sears, Roebuck & Co. to sell their radial tires through Sears stores, it soon became evident that when these tires were fitted to U.S. vehicles that were not radial tuned, many consumers became dissatisfied with them because of ride harshness, boom noise and a too rapid steering response, which is typical of radial tires fitted to untuned vehicles.
In some cases, consumers returned the tires to Sears, while others kept them despite their drawbacks because of their much longer tread life (50,000 miles was not unusual), a definite economic advantage. Eventually Michelin learned, as did the U.S. vehicle manufacturers, which in time also learned how to radial-tune their vehicles.
However, it was only when Ford began to fit Michelin radial tires on its 1970 Lincoln Continental MK3 as standard OE that radialization really began in North America, and I am proud to say that I was a major contributor in this development because of my work at Ford from 1955 to 1970 on tires, and including radial-tuned vehicles (the radial-tuned suspension and other vehicle sub-systems).
The outcome of this significant eventand the massive capital investments required for the switch to radial tires from biaswas that the U.S. tire industry suffered a major shake-out. Today only one of the original OE tire producers of that era remains in independent hands, Goodyear, the others having been taken over by foreign tire manufacturers: Uniroyal/Goodrich by Michelin, General Tire by Continental A.G.; Armstrong by Pirelli & C. S.p.A.; Firestone by Bridgestone Corp., and so on.
In the process, my original prophecy and Mr. McNamara's 1959 wishes to procure tires capable of delivering 50,000 miles for Ford vehicles were fulfilled.
Apparently years later, in 2006, Francois Michelin said in his acceptance speech upon being inducted into the Tire Industry Hall of Fame: It is important to know the true value of money, which is not an end unto itself.
I agree, and the tire and vehicle industry must continue to reinvent itself. But what have we really achieved in this regard since the radialization took place in America in the early 1970s?
Because the radial tire architecture represented, in my view, such a significant technological event that provided consumers equally significant economic and technological advantages over bias tires, as well as significantly improved road/tire/vehicle/ driver system operations, that I called its promotion Marketing Technology.
It is also appropriate to mention at this point that the radial tire created its own market, once the public experienced its advantages.
For some time now a percentage of U.S. consumers has been complaining about poor tire tread life, particularly the very short tread life of ultra-low section height radial tires. Such expensive tires have aspect ratios ranging from 25 to 30 series.
The trend toward ultra-low-profile tires began in the 1990s but gained momentum about a dozen years ago when the major vehicle makers started mounting them OE on some of their sportier models. Today the practice is much more widespread.
In a paper I presented at the 2004 International Tire Exposition and Conference in Akron titled 55 years of radialization, I stated: It remains to be seen if this trend persists, if long-life tires (50,000 miles and more) which radial-ply tires can provide, will remain a selling point, and if consumers will accept radial-ply tires providing bias-ply tire mileage but at radial-ply tire prices.
I also stated in the same paper: If radial ply tires cannot fulfill the original promise of long life, hence providing an economic advantage to consumers over bias-ply tires, are we going to see the industry having to produce twice as many tires as needed, demanding twice the amount of raw materials and energies and resulting in twice the number of scrap tires and disposal problem? If this low mileage trend persists, what was radialization all about?
As for tire retail prices these days, since I presented the above-mentioned paper, the country has experienced not only a serious economic downturn and severe unemployment, but tire retail prices have continued to escalate unabated.
In my opinion, tire economics also should include retreadability or remanufacturing.
In a paper I presented at the Tire Society in Akron in March 1984, I stated: It is the remanufacturing (retreadability) of a tire that is 'the real measure' of the original tire quality.
I still stand by this standard today. In fact, you can observe, even today, 45 years after U.S. radialization began, pieces of tire treads/belts that have detached themselves from the rest of their tire structure, along the sides of the roads. This might be a sign of still-insufficient tire structural integrity retention, and this after all these years and in spite of the now widespread use of cap plies on radial tires to contain the steel-cord belt.
In view of this current situation, I would like to see a comprehensive and totally unbiased comparative road/tire/vehicle system test conducted between radial and bias tires, from which the remanufacturing potential of these two types of tires could be determined accurately. This could benefit the percentage of any population that is economically challenged, offering tires that cost half as much, can deliver a minimum of 30,000 miles and can be retreaded.
There are good tools availablesuch as holography, shearography and X-rayto determine, among others thing, the remanufacturing potential of tires. I suggest to use such tools in connection with conducting the comparative test I recommended above as well as visual inspection and precise dissection.
We hear a lot about low rolling resistance tires these days, but there are limits to that. We also hear a lot about a U.S. government-mandated average fuel consumption of 54.5 miles per gallon by 2025. Such objective would be extremely difficult to achieve, in view of the fact that today 55 percent of all light vehicles operating in America consist of light trucks, SUVs and cross-over vehicles that are not really conducive to good fuel economy.
Low rolling-resistance tires apply particularly to relatively low-mass, low aerodynamic-drag vehicles, driven fluidly at relatively low speeds on straight and flat roads, and powered by efficient low-friction power trains featuring relatively small engines, and with minimum negative effects of winds, hills and pavement friction characteristics.
Keep in mind, however, that tire-to-pavement friction is needed to derive good tire tread-to-road surface traction.
I also must clearly indicate that the positive effects of low rolling-resistance tires on vehicle fuel savings have been greatly exaggerated for marketing and sales purposes, and are of course affected by the total weight of the vehicles on which they are fitted, as well as the (in)efficiency of certain vehicle chassis and powertrain systems and the overall vehicle aerodynamic drag.
In my view the radial-ply tire architecture today is not sufficiently exploited. In a column in a previous issue of Tire Business (Sept. 1, 2014), I mentioned: Today we are confronted with some unfinished tire/vehicle system engineering challenges, and I outlined eight principal points requiring immediate attention.
Among these are exploiting radial tire architecture for improved performance, simplifying the tire design and manufacturing process and educating consumers in tire/vehicle system technologies.
You may want to reread that particular section, or maybe even that whole column.
The answer is YES. Bias tires are still in use today in certain parts of the world, for example in India, which has, in general, poor roads and streets, many of which are unpaved. In countries that are economically challenged, damaged or worn-out tire replacement is strictly a matter of economics, and for many, affordability.
Well-designed, -produced and -applied four-ply rayon or polyester cord-reinforced bias tires of 78 to 80 aspect ratios, coupled to high precision 70-percent wheels, inflated at 28 PSI and deflecting about 20 percent of their inflated free section height under load, should provide a tread life in the order of 30,000 miles when operating on relatively smooth, well-maintained and straight/flat roads with normal levels of abrasiveness.
However, when operating on unpaved, highly curved, highly abrasive roads, the resistance to treadwear of any tire, bias tires included, is diminished.
One of the major attributes of bias tires is their low impact, harshness and boom noise levels, as well as their high tolerance of the effects of poor and curved roads on tire structural integrity retention. This is due to the fact that bias ply tires do not have belts that can separate from the rest of the tire body, hence the remanufacturability (retreadability) of bias tire casings is higher than with radial tires using steel-cord belts.
A few years ago, following some pertinent observations, I concluded it would be worthwhile to undertake the development of special bias tires, produced according to radial tire disciplines. These beltless bias tires, which I called hybrids, would be capable of delivering 35,000 to 40,000 miles of service and would be retreadable.
Also, and of great importance to the economically challenged mentioned above, these hybrid tires could be sold profitably at prices significantly lower than steel-belted cap-plied radial tires. Nothing ever came out of it, but I still think that it is a good idea, and wonder, if anybody else has been thinking about it.
Speaking of alternative tire concepts, the industry has been flush recently with concepts that some suggest could replace the steel-belted radial. Among these are a number of non-pneumatic types, which calls to mind experiments dating back to the early 1900s on similar ideas.
I'm planning to cover some of these ideas from the pastand some from the present, including the prospects for a polyurethane-based tirein a future column. Stay tuned.
Jacques Bajer is founder and president of Tire Systems Engineering Inc. in Grosse Pointe, Mich., a consultancy dedicated to road/tire/vehicle systems technology. The French-born engineer was an active participant in the evolution of the automotive and tire industry. His work at Ford Motor Co. from 1955 to 1970 led to the development of the tire uniformity grading machine (1962) and the low-profile tire (1964). Mr. Bajer also was a key figure in the radialization of the American market. The holder of many patents on tire production and design, his work earned him a spot in the Tire Industry Association's Hall of Fame, to which he was inducted in 2006.