Today: Does Fix-A-Flat Really Work? - Car Talk

Dear Car Talk:

I'm wondering if you would comment on tire-repair-in-a-can products like Fix-A-Flat for emergency tire repair. I am in the Navy and am trying to ensure that my wife has a backup plan to changing a tire if AAA is delayed for several hours (not a good thing with a 4-year-old in the back seat). Do these products work?

-- Jeffrey

They often do work. There even are a few small cars that come equipped with that stuff in the trunk.

In the first Fiat 500 we test drove, instead of a spare tire I remember finding a can of "flat fixer," a little air compressor and a bottle of Filippo Berio Extra Virgin Olive Oil. The oil must have been for dipping your bread in while waiting for the tow truck if the flat fixer didn't work.

If you have a small hole in the tire -- from a nail, for instance -- or a slow leak around the rim, products like Fix-A-Flat can work well as temporary solutions. The can contains a liquid that's injected into the tire, along with additional air. Once inside the tire, the slime hardens against the inside of the tire and, hopefully, covers up the hole.

But it's a temporary fix. The idea is that it allows you to get off the side of the road and get home, or get to a tire repair place.

And it won't work for every flat tire. If you have a gash in your sidewall, or you backed over the spikes in a rental car return lot, or sustained any serious damage, a can of Fix-A-Flat is not going to help you at all. Unless, perhaps, you can stuff the can itself into the hole.

And there are other limitations to keep in mind. The stuff freezes when it's below 32 degrees. So if you live where it gets cold, and you keep it in your trunk, you may have to cuddle the can to your bosom in the passenger compartment for an hour or two until it turns back into liquid.

Also, there's not much additional air in that can. So if your tire is really flat and riding close to the rim, the contents of the can won't give you enough air to drive on.

You can address that by keeping a little compressor in the car, like the one Fiat provides. It's powered by the car's power point (aka cigarette lighter). It's slow, but it gets the job done.

So, leaving a can of Fix-A-Flat in your wife's car, along with a compressor, is not a bad idea, Jeffrey. It may get her out of trouble someday. But because it won't work on every tire failure, you want her to have roadside assistance, too.

And even when it does work, make sure she knows that she'll need to get the car to a mechanic who can fix the tire properly with a patch or a plug.