Tuning spreads along the world roads at the speed of lava after the eruption of Vesuvius. Thousands of official dealers, network services and garage workshops will willingly take on the transformation of the car, whether it’s a domestic “classic” at the price of a TV set or a premium sedan at the cost of a solid apartment in a world capital.
Hundreds of exhibitions, festivals and competitions are held annually throughout only our country. But does all this mean that there are no “white spots” on the tuning map? Sure, no.
Now we will talk about a popular phenomenon that, nevertheless, still raises many questions – tire tightness, or stretch.
What is it?
Simply put – rubber is a “house”, when a tire of a smaller width is put on the wheel than calculated by the manufacturer. For example, a 195 mm tire instead of a 255 on a 9-inch wide rim. This is achieved by tensioning the tire sidewalls, the so-called profile. Now the profile isn’t perpendicular to the contact patch, but at an obtuse angle.
In most cases, when stretched, the inner and outer edges of the disc bulge outward. Now that the word “stretch” is associated with more than just jeans, it’s time to answer the main question.
Depending on the area of use, the answer will be different. Historically, the method of stretching narrow rubber on a wide disc appeared almost simultaneously in Germany and Japan at the end of the last century. But if in the east drift was the cause, then in the old world it was legislation, or rather attempts to bypass it.
In Germany and Belgium, the law prohibits the operation of cars in the event that the contact patch is outside the arches – this left no choice for lovers of wide track. By taking the disc out of the fenders, the stretch allowed the tire to remain inside and everyone was happy.
As for drifting, the interference is appropriate here for several reasons: a narrow tire is easier to break into a skid, it costs less, and due to the angle, it breaks less under lateral loads arising in sliding.
How and what to stretch?
Let’s say you’ve made the decision to stretch. What do you need for this? First, define your goals. If this is drifting or another sports discipline where handling is at the forefront, then you should start by looking for tires in the right parameters, after which the required disc width will become clear.
On the contrary, if appearance is more important than driving characteristics, then you should look for discs with the maximum width that the wheel arches can accommodate. Let’s say it’s 10 inches in seventeenth diameter. It’s recommended to install tires on them at least 275 millimeters, which means that a width of 245 or less is suitable for stretch.
It should be borne in mind that the height of the profile of the tire has a stronger effect on the ability to pull than its width. Low profile tires have stiffer sidewalls, which makes it harder to stretch, but give a more dramatic stretch compared to 50% or more section height.
How to stretch tires?
Tuning wheels with a “house” effect is not within the power of all tire specialists. To do this, the workshop must have special equipment, and the employees must have experience working with non-standard tires. Sometimes, the car service may refuse to perform tension, and it’ll be much better than to agree and damage your tires.
The first option for filling tires with air provides for preliminary sealing of the free space using an auxiliary chamber. This is a rather complicated procedure that not all tire fitters are familiar with.
It’s more technologically advanced and easier to use explosive pumping or ignition of a combustible mixture. For instant filling of the tire with air, cylindrical receivers with a volume of 20 liters are used. It’s enough to open the tap for a large volume of air to enter the chamber in a tenth of a second. Arson makes it possible to obtain high pressure by expanding the heated air.
For this, the entire inner circumference of the disc rim is wetted with a flammable liquid, after which a torch is set on fire. At the same time, it’s necessary to supply air through the nipple, which will prevent the tire from returning to its original position. As soon as the tire reaches the required position on the disc, the working pressure inside is brought to the level of 2.5-4 atmospheres.
Summarizing the above, here are the advantages and disadvantages of stretch tires.