Run Flat

Advantage of Run Flat Tires

What is a run flat tire and what are the advantages, I hear you ask? These are a couple of the main questions that we answer in the below article. With an increasing market share tire makers including Firestone, Goodyear, Bridgestone and Dunlop are developing new technologies to cater for this specialized niche. Vehicle owners are waking up to the advantages of run flat tires and this particular type of tire is becoming popular in many car, truck and SUV vehicles. We investigate the technology, performance characteristics, highlight the pros and cons, and offer buying advice on run flat tires.

What are Run Flat Tires?

The main advantage of a run flat tires is the ability to enable vehicles to run even when the tire is punctured and the air has been lost. The advantage of not having to pull over and change your spare tire is obvious. The main three systems all resist air deflation in a different way with the aim of allowing the vehicle to continue to be driven. The only caveat of such a run flat tires are the restrictions on speed and distances placed on each tire by the manufacturer. High Performance Tires characteristics differ from tire to tire so its important to view the specification guidelines for each manufacturer to determine the optimum run flat tires for your vehicle.

Why Choose ?

Think back to your last puncture, blow out or run flat tires you had to endure, pleasant experience? Of course not, but this eventuality affects all vehicles owners period. It always seems to happen when your rushing for a meeting, late for an appointment or picking the kids up from school. The stress and inconvenience of this event is one that no-one looks forward to and if you’ve been fortunate to avoid it, I’m sure you would agree its a situation you want to prevent. Changing a flat tire in the dark, pouring rain or a busy city center holding traffic up is an incident made worse if you cant find your jack, your spare maybe flat or worse still missing.

Run flat tires can temporarily keep your vehicle on the road until you reach your destination, service station or a garage. Therefore providing the driver with more flexibility on selecting the location to repair the damaged tire. This can eliminate road side changes and hence improve the safety aspect of driving.

Although this sounds like a no brainer there are other considerations that need to be discussed before deciding if run flat tires are right for your motor. Read on to explore the advantages and disadvantages of run flat tires.

Buying Considerations

Ok you are interested in buying a set of run flat tires possibly as an after market upgrade or your looking to buy a new car that has run flat tires as a standard how do you choose the right tire for your budget?

Type of vehicle and everyday journeys

There are several different variables to consider before parting with your money. Its important to analyze your average time spent on the road and to determine if you clock up miles on highways and freeways or are mainly on local town journeys? Is your vehicle a light truck, SUV, standard family car, tractor or executive vehicle? Do you drive at high speed at every opportunity?

Driving conditions Snow and Ice or Sun and Rain
Driving conditions differ from state to state and due to the uncertainty of today’s random weather conditions we often need to prepare for worst case scenarios. How many months of the year are your roads covered in snow or ice? are you mainly driving in a hot climate with occasional rainfall in winter and autumn months or a typical North American varied climate?

Conventional Tires Tread v Run flat Tires Tread

One factor which is widely accepted is that regular tires will cover 2-3 times more miles than run flat tires irrespective of brand. One way to view this is to consider that 4 conventional tires will last as long as approximately 10 run flat tires.

Performance Characteristics
Results have shown that certain run flat tires have up to 20% higher rolling resistance because of extra material and increased mass of the tire. Conversely, this can reduce tire deformations and has the opposite effects of reducing rolling resistance and will improve fuel efficiency.

Driver experiences have been mixed on run flat tires with some complaining of premature or uneven wear on tread. Then you have to factor in the high replacement costs and limited selection and in some eyes these tires lose a little of their marketing appeal.

Many new car manufacturers that fit run flat tires as standard such as BMW and Toyota don’t fit spare wheels so please be aware that you don’t have the added security of a spare in case of breakdown. The obvious benefits of no spare wheel is the reduction in overall vehicle weight and therefore increased fuel efficiency, reduced carbon monoxide emissions, better handling characteristics and performance.

Run flat tires can also provide the driver with a stiff ride experience which is often coveted in sports cars and performance vehicles but not welcomed for the family executive car especially in real-world driving. The firmer ride is attributed to the reinforced sidewalls. Logically, car suspension systems are designed for the very opposite of what run flat tires provide. Whether this is a significant variable to outweigh the obvious safety and convenience benefits only you can decide.

There are three main technologies used in the manufacture of run flat tires, self-supporting run flat tires, self-sealing tires and aux supported run flat tires systems. All three benefit greatly from tire pressure monitoring systems (TPMS) to constantly check for the loss of air.

1. Self-Supporting Run Flat Tires

Pros – This type of run flat tires are generally used on all light trucks and cars. The advised driving limitations on these types of run-flats are speeds of 50 mph for approximately 50 to 100 miles before having to change the tire.

Cons – Location of the puncture is pivotal in whether the tire can be repaired or runs safe. Sidewall punctures are open to both risks so please consult the tire user manual for your brand of tire and rims.

Cons – Reduced performance issues due to a larger weight penalty that is carried on the outer sidewall.

2. Self Sealing Run Flat Tires

Pros – Small tears caused by screws and nails can be automatically repaired by the inner tire extra lining. The lining within the tire initiates a self seal as soon as the tire begins to deflate. This feature can repair most smaller holes and can be driven on with little loss in performance or at worst a very slow puncture. Newer tires that are entering the market replicate the same inner lining technology by use a sealant compound. The compound is released when the air pressure drops and the sealant forms a protective layer around the hole by utilizing the rotational force as a distributional mechanism.

3. Aux Supported Run Flat Tires Systems

The most expensive of the three technologies but offers a superior performance and increased safety level over the other two due to the reinforced sidewall design. The aux system is designed around a special combination of wheel and tire utilizing a tire support ring that is attached to the wheel. When the tire loses pressure the additional support ring reinforces the tire tread around the full footprint of the tire and shifts the main mechanical weight away from the tire and onto the wheel.

Cons – The disadvantage to auxiliary supported systems is one of expense. With the system being solely dependent on a unique rim and wheel package, the aux system is one usually reserved for high performance and executive cars. The system will not accept standard tires and major tire manufacturers produce this system in lower manufacturing volumes because of the demand.

Market Share
Run flat tires have a very small market share at approximately 3% in the US and Canada. With BMW being the largest fitter of run flat tires as original equipment on new models. Other tire and car manufacturers are researching and developing their wheels and tires to improve tread depth, tread design and improve tire repair.

Costs and Conclusion
As highlighted in this article, if cost is your main overriding factor then you will be focus your attention on conventional tires. They last longer on a tire per tire basis, you’ve a greater selection of choice and more readily available online and in local resellers. Run-flat tires are produced in lower volumes, rarely repairable and are more expensive compared to their cheaper conventional counterparts.

If safety is paramount when choosing your new tires then the added safety aspects and convenience benefits far outweigh conventional tires. Deals are to be had when purchasing run flat tires especially when buying a full set, but regardless of the discount you will always pay a premium over a conventional tire set.

Run Flat Tires

Specialist Tires – Run Flat


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Posted by Michael - October 7, 2011 at 3:50 pm

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