Even if you know how to change a flat tire, chances are pretty good you'll run into problems you're not prepared for. Flat tire repair is never predictable, but this guide can help you survive the ordeal.
Your car or truck owner’s manual shows you how to change a flat tire, assuming a best-case scenario. But the real world includes all kinds of surprises: lug nuts that won’t budge, a wheel that’s rusted to the hub or a spare tire that’s so underinflated, it’s useless. Don’t think you’re out of the woods just because you have roadside assistance. Because if you get a flat tire in an area with no cell phone coverage, or the service is so backed up that it’ll be hours before they get to you, you just might have to change your tire yourself.
To help you survive a flat tire ordeal, we’ve collected these tips. Some we’ve taken from our own ugly encounters, and others we’ve learned from our readers.
So slow down! The spare-tire manufacturers are serious about their 50-mph maximum speed limit. Get your flat tire repaired or replaced right away because space-saver spares are designed to run for only 50 to 70 miles.
Carmakers use two methods to secure plastic wheel covers: spring clips and screw-on plastic lug nuts. If you don’t know which type is on your vehicle, try turning one of the plastic nuts with the socket end of your tire iron. If it rotates, you have the screw-on type. Unscrew all the plastic nuts and lift off the cover.
If the nut doesn’t turn, you have the snap-on style. Those have to be pried off, and that’s where some people get into trouble. If you jam the tapered end of your tire iron into a weak area on the cover, you’ll break it to pieces. So be sure to pry behind one of the larger spokes and twist until the cover pops off.
If you don’t routinely top off the air pressure in your spare tire, don’t be surprised if it’s severely underinflated when you need it. Driving on a severely underinflated full-size spare is unsafe, and driving on an underinflated space-saver spare is downright dangerous. Solve that problem by keeping a plug-in tire inflator in your vehicle at all times (one choice is the Slime 12-Volt Digital Tire Inflator, No. 40022, about $30 on amazon.com).
Start the engine, plug the unit into your power port and bring the spare tire up to the recommended pressure (found on the decal inside the driver’s door area) before installing it on the hub.
To avoid theft, many cars have one special lug nut on each wheel that requires a special “keyed socket” to loosen it. If you can’t locate the key when you have a flat tire (or another driver in the family isn’t aware of it), it won’t be possible to remove the wheel. You’ll have to use Fix-a-Flat, call for roadside service or have the vehicle towed to a shop. That can cost upward of $200. So make a point of keeping the key in a safe place, like the glove box, that is known to everyone who drives the car.
If you don’t rotate your tires every 5,000 miles, your wheels may be bonded to the hub by rust. Here’s a way to knock the wheels loose, submitted by one of our readers.
With the lug nuts loosened about three-quarters of the way, grab the spare by the center hole and use it as a battering ram. Swing it horizontally with all your might so it strikes the stuck wheel at the 12 o’clock position. Repeat the blows at the 3 o’clock and 9 o’clock positions until the wheel breaks free from the hub.
If you’re not confident that you or the driver can change a flat tire, buy two cans of aerosol tire sealer from any auto parts store (Fix-a-Flat is one well-known brand) and keep them in the vehicle. The cans are sold in several sizes for compact, standard and truck-size tires. Tire sealants work on tread punctures 3/16 in. or less in diameter. They won’t work on sidewall punctures, blowouts or any other catastrophic failures. You’ve got little to lose by trying sealant.
You can greatly increase your chances of a successful seal if you can find the puncture site and move the vehicle until the leak is facing down. If you see the culprit, don’t remove it; it’ll help seal the hole. If the can is frozen, thaw it with the defroster or floor heater vents until the contents move freely when shaken. Then fill the tire following the directions on the can. If the rim doesn’t lift off the ground after using a second can, the puncture is too large to be sealed and you’ll have to call for help.
Top off the air pressure as soon as possible. If you have a tire inflator on hand, do it now. This is a very temporary fix, so get the tire repaired professionally ASAP. Tire sealant must be removed within three days or 100 miles, whichever comes first. Inform the tire shop that you’ve used tire sealant so no one breathes in the propellants (not flammable, but not healthy either). The shop may charge extra for cleaning the sealant from the tire.
Many DIYers think they can permanently repair tire punctures with just a plug. They’re wrong. A tire plug is just half of the repair. The tire’s interior liner must also be repaired with a patch, and that means a trip to the tire store. Skip the patch and you risk a catastrophic blowout.
Whether you change your tire yourself or rely on a tire sealant, keep these “mission-critical” items in your vehicle at all times.
Wheel chocks. Keep your car from falling off the jack, especially on slopes.
Plug-in flashlight. Dark nights can make it impossible to see what you’re doing.
Gloves. Good to have all year long, but critical for handling cold metal in subzero temps.
Tire inflator. You’ll need this to fill low spares and top off tires repaired with Fix-A-Flat.
There’s no way you can loosen the lug nuts once you raise the vehicle—the tire will just spin. Instead, break loose—but don’t remove—the lug nuts while the tire is still on the ground. To save your back, place the tire iron on each lug nut so the handle is in the 9 o’clock position. Place both hands on the tire iron and push down with all your might. If that doesn’t work, use a downward bouncing motion with your weight to break the nut loose.
