What are Run Flat Tires
What are Run Flat tire and how they work: We all had a flat tire at certain point and somehow always seem to happen at most inconvenient of moments. When that happens we are left with two choices: call a tow truck and wait for couple hours or get dirty and use the spare tire. Problem with second choice is most don’t know what a spare tire is, let alone changing it.
Invented in 1980s, Run Flats Tires were designed exactly for these types of situations. Run Flat tires also create more trunk space by removing spare tire altogether. Cheaper for manufacturers as spare tire, vehicle jack and tire lug wrench are gone. Its one less expense per car, which looks small but if added up for millions of production cars it becomes quite significant.
Run Flat tire symbols is RSC, it means Run-Flat System Component and is imprinted on tire sidewalls.
How Run Flat Tires Work
Regular tires need a certain air pressure to work. If air pressure drops, regular tires will deflate and vehicle cannot be driven anymore or tires will be destroyed. Especially on high speeds a flat regular tire will often completely disintegrate.
Run Flat tires have a reinforced sidewall, designed to keep vehicle weight when tire air pressure drops to zero due to leaks or punctures. Reinforced sidewall enables Run Flats tires to work with no air pressure. Run Flats can safely drive up to 70Km/h, preventing tire disintegration if a puncture happen on highway speeds.
Flat tire speed might vary depending on tire design and manufacturer. Consult vehicle manual for specific details, or tire manufacturer if you changed your original vehicle tires and were provided a tire booklet.
Types Of Run Flat Tires
There are two main designs of Run Flats tires: Self Supporting and Ring Supported.
1) Self supporting tires
Self Supporting tires have reinforced and thick sidewalls which will handle vehicle weight in case of tire deflation. Tire sidewall is built with thicker and harder rubber to support vehicle weight with speeds up to 70km/h. Detailed post and video from tire manufacturer Continental about Self Supporting Tires.
2) Ring Supporting tires
Ring supported tires have a hard rubber ring installed on center of the wheel (or center of tire). In case of tire deflation vehicle weight will be handled by supporting ring. Ring supported tires are heavy and have a harsh ride due to extra ring weight. Also, tread wear of ring supported tires is higher when compared to normal ordinary tires, shorter life.
Advantages Of Run Flat Tires
Run Flat Tires Safety
Tire blow outs on highway speeds are reduced with Run Flat tire use. However, even though Run Flat tires might prevent a blow out on high speed, however, will still have to be replaced after a puncture as tires are destroyed in these situation. In any case, run flats are much safer than ordinary ones when loss of tire pressure occurs in high speed, highway driving as an example.
Driving with a Flat Tire
Primary advantage of Run Flat Tires is: if your tire is punctured, you can still drive. No need to pull over and call a tow-truck or spend time on the side of a high speed highway installing a spare tire. It improves safety, as you dont have to deal with cold weather, rain or having to get out of your vehicle in a dangerous area to deal with a flat tire. You just keep driving until you reach your destination.
Space and Weight Saving
Run Flat tire secondary advantage is space created by removing spare tire, wheel lug wrench and vehicle jack. Removal of tools and spare tire reduces vehicle weight, and will marginally or technically improve fuel efficiency. Not so much in real life but manufacturers like improvements in fuel efficiency, however small and insignificant.
However, this is debatable as a lot of people feel safer with a spare tire. Especially on remote areas where there is no AAA or CAA to call…or no cell phone service at all and likely no Tim Horton’s either.
Disadvantages Of Run Flat Tires
No Spare Tire
While driving on flat tire is all good, nothing beats a spare tire. There are a lot of people which feel safer with a spare tire. Especially on remote areas where there is no AAA or CAA to call…or no cell phone service at all and likely no Tim Horton’s either. Anyways, most dont know how to remove or install a tire, so there is that.
Run Flat Tires Price
Run Flats are more expensive than regular tires, by quite a bit. Tires also last less than a regular ones, probably about 10,000km less in average. Run flat tires have a hard ride by design. Manufactures have to use softer materials on tire surface to compensate internal hard rubber and soften ride as much as possible.
Tires made with softer rubber are consumed faster and have shorter tire lifespan. Sport cars as an example come softer rubber on their tires and do not last as much as regular ones. Add to that run flat tires can not be repaired and price adds up.
Run Flat Tires Driving Experience
Driving comfort is not good, its quite bad actually. Compared to regular tires, Run Flat tires create a harsh or rough driving experience. Quality of ride will suffer as a consequence sidewall thickness of Run Flat tire and/or center reinforced rubber ring. There also complains of uneven wear of Run Flats tires.
Run Flat Tires Weight
Runs flat are heavy, due to complicated construction and amount of rubber used. Weight will affect fuel economy, however not by much, probably 1% or so.
Run flat tire has advantages and disadvantages and is a compromise between price/ride quality and safety/convenience. In the end, it will all depend on personal preference, needs and budget, as per everything else.
Conclusion
Run flat tires have their advantages and disadvantages. At the end it comes to personal preference and if you can afford to spend extra for tires on your car.
In any case, tires are interchangeable, you can change to ordinary tires on a car which had run flat previously and vice versa. However, if you change from rum flat tires to ordinary tires and dont have a spare tire in your car then you will lose ability to drive if you suffer a tire pressure loss. You will have to tow your car.
How Run Flat Tires Work by tire manufacturer Bridgestone.
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