Answers

1. 

   178

   

   7-26-11

   MrFF says:

   Running on empty

   Run-flat tires are a relative newcomer to the tire market with some manufacturers even installing them at the factory, BMW being one of the more notable ones. Run-flats can free up the space and weight taken up by a spare tire and jack and give you the peace of mind of knowing that you don’t have to change a flat… in the rain… on the side of a busy freeway… at night.

   Like any product, run-flats have their drawbacks as well as their advantages. Before we get too far into both, let’s look at how run-flats actually work.

   The tech-y bits

   Run-flat tires are divided into three basic types of technology, each with their own pros and cons. In no particular order, they are:

   • Self-supporting: One of the most popular types, the self-supporting tire has a stiff, reinforced sidewall (the bit of the tire that has all the writing on it and seals to the wheel) that allows it to support the vehicle’s weight while driving, usually up to 50 miles at up to 50mph.
   • Self-sealing: This type of run-flat tire has a special sealing compound that lines the inside of the tire. In the event of a small puncture, this liner fills in the hole left behind and prevents the air from leaking out in the first place.
   • Auxiliary-supported: This type has a support ring that is attached to the wheel itself that can take the weight of the vehicle if the tire goes flat. They require special wheels to be used.

   The ups and downs

   Good things about run-flats:

   • You don’t need to get out of your car to change a flat in a risky situation (side of the freeway, bad weather, neighborhood of dubious inhabitants).
   • If you’re disabled and can’t change a flat, you can drive long enough to get to someone who can help.
   • No need to have a spare tire and a jack taking up room in the trunk/cargo compartment.

   Not so good things about run-flats:

   • They’re expensive.
   • If your car doesn’t already have the tire pressure monitoring system (TPMS) installed, you’ll need it. With run-flats, there is no way to tell if they’ve gone flat without checking the tire pressure.
   • They generally give a more firm ride, transmitting more bumps and road noise to the passengers.

   The bottom line

   Without knowing your exact situation, vehicle, driving habits, location, and so on, I can’t tell you “yes” or “no.” However, with the knowledge I’ve provided now you can make your own educated decision on whether run-flat tires are the right choice for you.