Tire Talk – Beware of Your Spare

Time and time again, tow truck drivers are called to change someone’s flat tire.

Now you wouldn’t think this is a big deal and it really isn’t…but some tow truck drivers see some potential safety and liability issues with that, especially when on the side of the highway and when your spare tire is a ‘space saver’ tire or ‘doughnut’ as opposed to a full sized one.

Flat TireNow most vehicles come with a spare tire of some sort, unless you are sporting “run-flats”, which I will talk about in another article. Some vehicles have a full sized spare but most only have a space saver tire, which is really just for emergency use only. There are a few things you should understand about your spare tire, especially the space savers.

1. They aren’t designed for highway use. The space saver tires are only rated for 80 km/h so taking them up to normal highway speeds could result in the tire overheating and failing. If that happened, you would once again be stranded on the side of the highway but this time you wouldn’t have a spare to lean on.

2. Space saver tires have a limited range of 80km to 150km depending on the manufacturer. Trying to drive it longer could result in another tire failure.

3. They have a much lower load capacity. The spare space saver tire should only ever be used on the rear of a vehicle. Most of your vehicle’s weight is in the front and because the spare tire is inflated to +/- 60psi, they can’t handle major impacts from dips in the road or potholes. They also aren’t very good at handling high lateral loads (hard cornering). This could result in the bead failing and a rapid loss of tire pressure.

By using a spare on the front, you could once again be risking a serious blowout and some manufacturers recommend that you NOT use the space saver tire on the front. Ideally, if you have a flat front tire, you should install the spare on the rear and move the good rear tire to the front to replace the flat. Not exactly practical because this would take you an hour or so to do and it would certainly not be safe to do this on the side of a highway.

4. It’s probably expired. Most people don’t realize that tires do in fact have a shelf life, which is about three to five years. This holds true not only for your spare but also your normal tires, too. Each tire has a four digit stamp on it indicating the week and year that the tire was manufactured. For example a stamp reading “0405” would mean that the tire was made in fourth week of 2005. Once a tire passes three years of age (used or not), the rubber begins to harden. Not only does the tread wear out significantly faster but once again, the tire is at risk of suffering tread separation. If the tire is old enough were cracks can be seen on the sidewall, it’s junk and far too old to safely use.

Tread seperation - Tow TruckIt’s for these reasons that I wouldn’t bother to change a flat tire with the spare that their vehicle came with. If I know the spare tire is old, or if it’s a flat front tire requiring replacement, it would be irresponsible and dangerous to put the spare tire on.

Instead, I would just call my auto club and get towed to a local tire replacement/repair centre.

Click here for more Tire Talk articles and drive safe out there.

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