tires February 10, 2017

Spare Tire 101

Spare tires are usually something you never think about until you need one. If you’ve ever been stranded with a flat tire before, you know how helpful they can be! Not all spares are created equal though, so let’s take a look at different spare tire options so you know what you’re working with in your own vehicle.

Full-Size Spares

Simply put, a full-size spare is an extra tire + wheel that matches the existing tires on the vehicle. It will be the same size and typically have the same amount of tread as a normal tire (although sometimes the tread will be slightly lower). Decades ago, it was the norm for all vehicles to come with a full-size spare tire. As more emphasis is placed on fuel efficiency and cargo space, full-size spares have begun to dwindle in the marketplace and have been replaced with alternative options.

Benefits – no compromise on handling or ride quality, and no need to get an immediate tire replacement

Downfalls – occupies the most trunk space, lowers fuel efficiency while being carried in vehicle due to heavier weight, and harder to install since full-size tires + wheels are bulky and heavy

Temporary Spares

Also called “donut” or “space-saver” tires, these spares are smaller with much less tread than a typical tire. (See photo – top tire is a donut, bottom is the full-size stock tire.) While they are optimized for your vehicle and shouldn’t be unsafe in terms of handling, they are not ideal since they don’t perfectly match the other tires. They do have their limitations, as they shouldn’t be used over 50-55 mph and only for about 70 miles. They are intended to safely get you somewhere that you can get a replacement tire.

Benefits – takes up less cargo space, lighter weight won’t hinder vehicle’s fuel efficiency as much as a full-size spare, and easier to install

Downfalls – won’t handle the same as your normal tires, you still need a tire replacement as soon as possible, and they have speed/distance limitations

Tire Repair Kits

Some vehicle manufacturers have ditched a spare tire altogether, and are offering shoebox-sized repair kits in their place (sometimes called a “mobility kit” or “inflator kit”). This kit consists of a small air compressor with an integrated sealant that will repair punctures in your tire, like fix-a-flat but a little better. To use it, you attach the kit to the valve stem and it injects the sticky sealant into the tire, seals up the puncture, then proceeds to re-inflate the tire.

Benefits – takes up less space than spare tires, negligible effect on vehicle’s fuel efficiency, and much easier to use than installing a spare tire

Downfalls – it can’t repair damage to the sidewall of the tire (or close to it) or a puncture larger than ¼ inch, it won’t help if the tire has come off the rim at all, and it’s not a permanent fix since you’ll still need to get to an auto shop asap*

*There is currently a debate as to how to handle this sealant. Some manufacturers claim you can clean it out of the tire and repair it; others claim you can’t clean it out and therefore need a replacement tire immediately.

Runflat Tires

A completely different approach to the flat tire dilemma is the runflat tire, which refers to the normal tires on the vehicle, not an extra tire. These tires have reinforced sidewalls and can maintain their shape after losing air pressure. Once they sustain damage, you can drive on them for up to 50 miles and up to 50 mph. They are designed to get you somewhere safely without you having to do anything in the interim.

Benefits – no need for a spare tire/kit so you don’t lose any cargo space, most convenient option since you don’t even need to get out of the car if your tire is punctured, and they are practically immune to dangerous sidewall blowouts

Downfalls – they offer a noisy + rough ride, lower fuel efficiency than normal tires, about 25% more expensive than regular tires, some manufacturers do not recommend repairing them so may have to get a replacement tire immediately, and many shops don’t stock them so they must be ordered in advance

If you’ve never looked in your trunk to find out what your emergency tire options are, there’s no time like the present. It’s best to know what you’re working with and how to handle it before you get into a sticky spot. If you have a full-size or temporary spare, it’s also a good idea to periodically check it for sufficient air pressure; it won’t do you any good if your spare is also flat! At Wiygul Automotive Clinic, we’re dedicated to keeping you safe on the road. Stop in to any of our 8 locations and our expert techs will be happy to inspect, repair, or replace your tires and get you back on the road in no time!

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