The tuner market began with hot rods, whereby vehicle owners wanted more excitement built into their vehicles at affordable prices.
To do that, the vehiclesfor example, the 1932 Ford Model Ahad to be easy to modify. The plus-sizing trend began much later, about 1995.
Consumers having their vehicles modified by the tuner market and plus-sizing movement should realize that the performance enhancements they expected are not necessarily delivered, except perhaps from a cosmetic standpoint.
This applies particularly to the replacement of tires and wheels that the car manufacturers selected for original equipment with significantly larger diameter wheels, up to 28 to 32 inches, and of wider wheel rim width dimensions, shod with tires of ultra-low aspect ratios, ranging from 25 to 30 series.
The lowest aspect ratio tire I ever encountered was 15 seriesa 365/15R24which, in my view, is simply ridiculous (see figure 1 on page 17). As for passenger car wheels, their diameter should never exceed 16 inches, and the rims should have a width dimension of 70 percent of the inflated tire section width dimension.
The history of significant changes in tire dimensional proportions actually began when Ets. Michelin, in 1937, obtained a patent for lower-aspect ratio tires of then bias-ply architecture, ranging from 67 to 85 series, at a time when the norm was 95 or higher, called super-balloon tires.
Michelin named the then-new lower-aspect ratio tires Pilot and has kept the name ever since.
Some of the vital performance characteristics of pneumatic tires depend upon the ratios established from three basic tire and rim dimensions1) wheel rim width; 2) inflated tire section width; and 3) inflated tire section height, all three for a given wheel rim bead-seat diameter and rim width dimension.
Another ratio also used, particularly by tire engineers, is the ratio of the inflated tire section-height dimension to wheel rim-width dimension. It is the tire section height that is of most and critical importance.
Years ago, I called this dimension tire stroke in an SAE (Society of Automotive Engineers) paper I wrote and presented in Detroit at the International Automotive Congress in January 1965. It was titled, Low Aspect Ratio Passenger Car Tire from A Vehicle Manufacturer's Point of View, and I dedicated the entire content of the paper to this type of tire.
Ford Motor Co. first used this type of tire in the U.S. as standard OE on the 1964 Lincoln and Thunderbird, in conjunction with larger diameter wheels. The previously used 14-inch wheels of narrower rim width were replaced with 15-inch wheels of somewhat wider rim-width dimensions.
Ford's decision, for which I was responsible, can be considered the start of the plus-sizing movement. The objectives of this then-controversial change were to:
c Provide room to fit larger diameter brakes, in order to reduce the vehicle stopping distance and provide improved brake cooling, as well as improved brake lining durability;
c Improve vehicle handling and directional stability;
c Reduce the tire rolling resistance, hence somewhat reducing the vehicle fuel consumption (under proper road/tire/vehicle/driver system operating conditions); and
c Somewhat increase the tire's resistance to treadwear.
All these changes were achieved without increasing tire inflation pressure.
Simultaneously, tire and wheel manufacturing precision and uniformity were also improved through a collaboration between Ford, wheel manufacturer Kelsey Hayes and Grotnes Metalforming, a machinery company that invented the true centric process, now part of Fontijne Grotnes B.V.
This collaboration resulted in the application of this true centric process, also first used by Ford, and was part of Ford's first-ever Tire and Wheel Engineering Product Acceptance Specification. These were the days when one could see that real progress was in the making, from which everyone eventually would benefit.
However, I deplore the current plus-sizing movement, which I believe is pushing a fundamentally good idea to extremes for the sake of appearance and/or marketingand at the expense of total tire/wheel system performance and affordability.
Although the tuner market and plus-sizing movements encompass many other vehicle modifications besides tires and wheels, this column will focus on tire/wheel systems, for lately, and with some exceptions, tires and wheels have become one of the most often and expensive vehicle components to replace.
With this column I aim at also making consumersand tire dealersmore aware of the consequences of using extreme plus-sized tire/wheel systems for the sake of making them the cosmetic components of the vehicle unsprung masses more than anything else. That approach ignores the detrimental effects this may have on vehicle dynamics, ride comfort, NVH (noise, vibration, harshness), tire/wheel system structural integrity retention, tire resistance to tread wear and traction, and, last but not least, prices.
There definitely are problems consumers will encounter with extremely low section-height tires on larger/wider wheels.
As I indicated earlier, it is the section height of a tire that is the most important and critical tire dimension. This dimension should be measured from the top of the wheel rim flange rather than from the wheel rim base, which has been customary.
I also like to mention that extremely low section-height tires are very limited in their radial deflection or stroke, as compared with tires of much more normal section height.
This means that the distance between the tire/wheel rim flanges in relation to the ground is reduced significantly, particularly when measured from the top of the wheel rim flanges.
Such condition renders both tire and wheel much more vulnerable to structural integrity degradations, particularly when the vehicle encounters severe road surface deteriorations, such as those commonly experienced in North America, due to the wide ambient temperature variations, pot holes, etc.
This can result in very costly tire and wheel replacement, and at times the replacement of other adjacent vehicle components, such as suspension arms, spindles, steering components, etc.
Although insurance policies are available today for wheelsparticularly since the plus-sizing movement took holdit must be recognized that had the wheels and tires involved been of more normal dimensions and dimensional proportions, the expenses to replace them when damaged might have been avoided.
This example shows the unintended consequences of using plus-sized tire/wheel systems.
Vehicle engineers with a sense of scientific integrity and professional conscience should have opposed such extreme trends a long time ago. To make matters worse, these ultra-low section-height tires are usually inflated at pressures of 35 psi or higher, instead of the pressures used universally with tire/wheel systems of more normal dimensions.
In summary, today's ultra-low-aspect-ratio tires are significantly stiffer than their more normal predecessors, which in turn has resulted in poorer vehicle ride, noise/vibration/harmonics and operating smooth-ness characteristics.
It is therefore needless to say that today's tire/wheel systemsas well as tire/vehicle systemsare in serious need of tuning, as I previously mentioned in the first column I wrote for Tire Business, titled When, why and how? Tires can't be ignored as important part of 'vehicle systems engineering & development' now and in the future (published Sept. 1, 2014).
At this point, readers should be aware that the higher the section height of a tire in relation to its section width, and the lower the tire inflation pressure (within the limits of stresses and strains the tire can take), the higher the tire tread to rim wheel base mechanical decoupling efficiency.
Maximum decoupling can be obtained only with radial-ply belted tires, whereby the tire tread and its sub-structure, the tire beltparticularly when made of steel cords in triangulated configurationare working independently from the rest of the tire cross-sectional structure (the tire sidewall zones). The amount of decoupling achieved is therefore a function of the tire sidewall-to-belt stiffness ratio, as I explained in more detail in an SAE paper I wrote for my then-boss at Ford in 1967, titled Application of Radial Tires for American Cars.
This also means that the stiffer the tire belt in relation to the tire sidewalls, the less the tire tread squirming in relation to the ground, and therefore the higher the tire resistance to treadwear. This is basic tire mechanics.
When well developed, produced and applied, radial-belted tires will operate at a high level of smoothness. Of all performance criteria, however, it is the tire's high resistance to treadwear, its low rolling-resistance characteristics and traction that consumers appreciate the most, because of the economic advantages radial tires offer as compared with tires of bias construction.
I am talking of good radial tires that feature long treadlife. However, this can be achieved only when the road/tire/vehicle/driver system operating conditions are also optimized, a difficult task indeed from my personal experience with it. But it can be done.
The tuner market and plus-sizing movements today represent how much America has changed over the last 50 years in its pursuit of maximizing profit with, at times, an excessively aggressive form of capitalism, and showing little consideration for the consumer.
We should all be outraged, but instead apathy and a rejection (or fear) of reality seems to be the norm. This smells Machiavellian to me. I encourage readers to look up Nicollo Machiavelli and read his views on the maintenance of power by a determined ruler indifferent to moral considerations, as expressed in his book, The Prince, written in 1513.
Historically, the strength of the U.S. capitalistic system was based on mobilizing capital linked to basic science and practical experience used for the benefit of the masses, and not only for the rich.
Once a product has been developed, including its manufacturing process, to the level of excellence required, then, and only then, can marketing and commercialization begin, and not the other way around. This is what Henry Ford had in mind with his manufacturing system based on the use of an assembly line, similar to the one first used in slaughterhouses.
At this point one question arises: Who is responsible for the vehicle warranty when something goes wrong with a vehicle that has been modified according to the tuner market and plus-sizing movements, and deviated from what was originally and sometimes painstakingly developed by vehicle engineers?
Keep in mind that consumers trust that vehicle manufacturers do the right thing in protecting them, particularly from a safety standpoint. I am very surprised, actually shocked, that nobody is speaking up.
And where is the National Highway Transportation Safety Administration (NHTSA) in all this?
In my view, the agency, years ago, should have investigated the consequences that the tuner market and plus-sizing movements could have on the consumer, technologically, economically and, again, from a safety standpoint.
Recently NHTSA could not even come up with a consumer-friendly tire-aging standard, even though the consumer has a right to know/be informed about tire performance criteria, since tires are vital components of the road/tire/vehicle/driver system safety and can structurally deteriorate with age, even when stored in a warehouse or in the trunk of a car (spare tire).
In view of NHTSA's inaction not to seek a safety standard for tire aging, how can one contemplate having tire and wheel service technicians and consumers correctly educated on the subject of tire technology and its ramifications with the vehicle, the road, the tuner market and plus-sizing movements?
In the words of the late Edouard Michelin: Tires are concentrates of technologies.
Imagine the following scenario: A customer comes into your tire and wheel dealership wanting to plus-size his tire/wheel package. You know what negative effects this would have on his vehicle (noise, vibration, harshness, handling, directional stability traction, lower fuel economy, etc...)
Are you going to tell him all this at the risk of losing a (substantial) sale, or are you. going to sell him what he or she wants?
Catch 22, or a question of moral and professional integrity? What would you do?
Don't get me wrong, I am a firm believer in capitalism, the pure and good form of it.
I say it is time to get our house in order, change the corporate culture, push vocational schools and apprenticeship programs and get back to basics. And yes, one individual can make a difference.
The media certainly have an important role to play, and I am grateful that throughout my career they have had the courage to print my opinions.
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.
Mr. Bajer has many patents on tire production and design. He realized that American automobiles would have to have both dramatic and subtle modifications to chassis, suspension, drive train and body panels to fully utilize and appreciate all of the advantages of radial construction. To this end, he helped develop the idea of power-train presence (power spectral density analysis), the acoustical tuning machine technique and the virtues of suspension compliance. His work earned him a spot in the Tire Industry Association's Hall of Fame, to which he was inducted in 2006.