Flat tires seem to show up at the most inconvenient times. You may have heard about runflat tires (sometimes called “zero pressure” tires), but do you know how they work? Did someone finally invent a tire that can’t go flat? Unfortunately, they aren’t totally invincible, but they can provide a safe alternative to keeping a spare tire in the vehicle. They do, however, come with some drawbacks. Let’s take a look at some various types of runflat tires, as well as their pros and cons.
What is a runflat tire?
These are tires that are designed to resist deflation when punctured. Once damaged, it’s typically ok to drive them at no more than 50 mph for up to 50 miles, giving you time to get somewhere safe. Once you are familiar with them and their positives and negatives, we would love your thoughts on whether they are best for your DC Metro area driving?
How do they work?
Over the years, runflat tires have taken a few different forms and have been manufactured by a number of brands. We’ll discuss these options in the next sections.
- Self-supporting tires: This is the most common type of runflat on the market today. The interior sidewalls are reinforced, making them much stronger and able to support the weight of the vehicle without air pressure. This allows the tire itself to maintain most of its structure, even in a situation of total air pressure loss. Some models of this type of tire include: Bridgestone Driveguard, Michelin Pilot Sport A/S Plus ZP, Continental ContiProContact SSR, and Yokohama AVID ENVigor ZP.
- Support ring tires: These tires have a firm interior ring that spans the length of the tire and can support the weight of the vehicle if the tire loses air. Michelin pioneered this technology and had a proprietary model called the PAX tire. Due to the complex nature of installing and removing these tires (they needed special equipment only found at dealerships), this style was eventually discontinued.
- Self-sealing tires: These tires have an interior liner that is viscous and sticky. It self-seals over punctures, similar to how fix-a-flat sealants work. The most common model of this kind of tire was the Continental ContiSeal, but because they weren’t as reliable as their counterparts, it was eventually discontinued as well.
Pros of Runflat Tires
They are a common alternative to carrying a spare tire, which is crucial for vehicles that are too small for one (think Corvettes and Mini Coopers), or people who really need the extra cargo space.
It also allows the driver to get to safety before having to change the tire – this is great if you get a puncture somewhere unsafe (like the side of a busy highway) or you don’t have the physical prowess to put on your spare (tires are heavy).
Self-supporting tires can also prevent dangerous sidewall blowouts; since their sidewalls are so heavily reinforced, they are practically immune to sidewall blowouts.
They reduce overall weight of the vehicle, which can lead to lowered fuel usage and thus offer fuel efficiency.
Cons of Runflat Tires
They are heavier than normal tires, and they have a much more rigid interior. Thad adds up to a loud, stiff, bumpy ride and lower tread life.
They are typically around 25% more expensive than regular tires.
They are harder to find and often need to be ordered in advance (majority of retailers don’t stock them in their shops).
Some manufacturers say that any damage to a runflat tire cannot be repaired, and the tire must be replaced once it sustains a puncture. Others, however, claim it’s ok to repair them, as long as the damage is small and not too close to the sidewall. The jury is still out on this one!