Tire Stretching: Just Say “No!”
Refuse to do anything that might compromise the safety of your customer’s vehicle.
The tire business is full of “fads.” They come and go. Some are harmless, but unfortunately some are dangerous. To put it bluntly, stretching tires is dangerous.
Some people will say they have done it many times, or they have it on their own car, and nothing bad has happened. Well, think about this: In some parts of the world, unscrupulous operators overload ferry boats every day. They stretch the capacity by loading 300 people on a boat engineered to carry 200. In the majority of cases, luckily, nothing bad happens. However, sometimes the ferry capsizes and many people die. Don’t believe me? Just Google “overloaded ferry” and see how many pages come up.
If you had a choice, would you travel on an overloaded ferry and risk your life? If not, why would you stretch tires beyond their engineered specifications and put people at risk?
Not as simple as it looks
Tires may look simple to the consumer but they are a highly engineered product, and you should know this. The tire, in conjunction with the wheel, and the air in the tire, support the weight of the vehicle and provide the only contact between the vehicle and the road – the contact patch.
As there are many tire manufacturers in the world, I am going to refer to the top five, who have been manufacturing tires since early in the last century. Their product catalogues contain tire specifications, including approved wheel widths, showing the minimum and maximum wheel widths on which a tire is to be installed.
Approved wheel widths, along with other tire specifications such as maximum inflation pressure and maximum load etc., have been established by an engineering process that involves rigorous testing for performance and safety standards. Many highly trained and experienced engineers have worked many months to design and test a product to work within the parameters, as specified.
A proper seal
For a tire to work properly and safely, it must hold air. Air can only be held in a sealed vessel. To become a sealed vessel, the tire must be properly mounted on a wheel, with a valve stem installed. The proper seal between the tire and the wheel is accomplished by the bead of the tire seating correctly on the bead seat area of the wheel.
The engineers designed the tire bead to seat perpendicular on the bead seat area of the wheel. Beads of stretched tires are not seated perpendicular on the bead seat area of the wheel, thus the proper seal is not accomplished. This can result in bead movement during an impact (pothole, etc.) causing rapid deflation of the tire. At high speeds, this can have tragic results.
Stretching the tire puts the sidewalls at angles outside the engineered specifications of the tire, thus overstressing the tire. This can cause tire overheating, sidewall separation, sidewall splitting, shoulder separation and poor treadwear. Google “tire stretching” and look at the images.
Respect the product. Do the right thing. Say “no” to requests to do the wrong thing. Explain that you are a tire professional and you will not compromise the safety of your consumers.