Are stretched tires legal and safe?
Stretched tires continue to be a controversial topic among car enthusiasts. Some believe using them is actually harmless, it adds beauty to the car while it can also withstand drifting at extreme speed. In contradiction, stretching tires can also be dangerous considering the impact tires have on handling, traction, braking, and safety of the passengers. So are stretched tires safe and legal? This is a question which is often asked over and over again.
Before we go into details let’s familiarize ourselves with tire stretching. It is mainly installing a tire on a wheel size that’s larger than what is specified for the tire, causing the tire to have to stretch to fit the wheels. Stretch tires became famous in VW circles and have now been widely used all over the world.
We plan to address this topic in a fair and open manner as much as we can. We shall look into the advantages and disadvantages of stretching your car tire.
Why tyre stretch for your car tire is not safe
Stretching always places your tire sidewall and bead through series of stress and strain which may hurt and cause your tire series of damage and can even make the bead to pop off while driving or during cornering. It can also reduce the lifespan of your tire. The reduced grip on the tire will also affect stopping as well as having an impact on your tread wear.
Tire manufacturers are against the idea of installing their products against or outside tolerance and the speed rating. Tires are constructed to fit a precise width of the rim; the tire load-bearing walls are usually constructed to be around 90 degrees tangent to the rim. Stretched tires are no longer within the degree tangent and are probably between 70 and 80 degrees due to the extra stress and strain which may create a degree of vertical instability especially during cornering. Tire stretch can cause the bead to burst open when the pressure drops which is more likely than in the case of a standard fitting tire.
Tire manufacturers are against the practice of placing the sidewall of a tire through extreme stress, which was not initially planned as part of the tire design. The association of British tires added that stretching a tire can cause the tire to dislodge from the rim after sudden impact. Therefore, it is reasonable to assume and conclude that stretching a tire is unsafe.
Reasons Why Tire Stretch Is Safe
Modern tires, especially low profile tires, are manufactured with better sidewalls capable of dealing with different kind of extra loads that might be subjected to it. In a tire filled with air, the car is adequately resting itself on the bubble of air so that the actual walls of the tire are less critical when it comes to strength. If the tire is correctly filled with the right air pressure, then there won’t be any fear of the tire blowing out of the rim when taking a corner or during driving.
Some modern car models now come with safe tire stretching: an example is Mercedes E class 2011-2015 model that can use a 19-inch tire. With the tire been cautiously stretched, there won’t be any problem when driving. Generally speaking, the debate whether stretching is safe or not should be disregarded since the rim size has been increased and standard tires widths are used.
To conclude on a decision is never going to be easy. There will always be those in favor, and those that will totally disagree. There are two types of stretching, Moderate and Excessive stretching. Moderate stretching is considered safe if the tire is averagely stretched, but if you extremely stretch the tire, then excessive tire stretch could be dangerous and harmful.
While the car specification also plays a significant role in tire stretching, some markers design tread pattern and sidewall construction for similar purpose while some don’t offer such service. The rim size and tire quality also play a significant role in tire stretching.
We will have to conclude that stretching a tire can be harmless in situations whereby the tire is not excessively stretched, while it is adequately maintained and moderately used. Most tires give a degree of protection to the rim so therefore the risks of damage from the curb will be nullified.
Is stretching your tire legal?
There are also questions raised weather tire stretching is safe or not because there is no precise law supporting or against the idea. The regulation differs from country to country as well as from state to state. From UK MOT point of view as of the time of writing, there is no specific law pertaining whether the stretched tire is legal or not. While it is believed to be illegal in Germany and varies from state to state in the United States.
Insurance companies tend to take caution on the legality of stretching a tire. They may accept or void your policy if not correctly informed in case of an accident and could directly attribute it to your stretched tires. Even if you do inform them, they may decline your application and refuse to insure your car. It all depends on the insurance company policy.
According to Motor Vehicles Approval Regs regulation, a tire should not be used on the road if not adequately maintained in such condition the “ tire must be fitted to a suitable wheel and suitable valve”. Its section 16 also states that tires should be of normal size and appropriate to wheels they are fitted.
The police have issued serious warnings and penalties under various construction and clauses. The agency also stated,
“To validate a failure, the tire or its fitting must violate The Road Vehicles (Construction and Use) Regulations 1986 road law.”
While the law is not specific about tread depth, ratings, speed cuts, etc. the fitting of a tire on an unsuited wheel rim is not explicitly covered. The lack of precise law either for or against stretched tires does not add clarity to the issue.
With excessive tyre stretches being ruled out, tire manufacturers may state the appropriate width rims and guides for those who are interested in stretching their tires. Speed ratings are usually lower in stretched tires and this should also be a factor on our minds. There is a degree of common sense to be applied during tire stretching. Check your tire makers for specifications and don’t go extreme. I believe tire markers will someday lecture drivers on how to stretch tires and start providing stretch designs suitable for their usage.