Driving Tips
Gary Anderson
 
What’s in Your Trunk – Managing a Flat Tire

So you’ve just had the disquieting experience of a flat tire while on the road. Maybe you’ve just hit a knee-deep pothole that cracked your wheel rim, releasing all the air from the rim-sealed tire. Or you’ve run over a nail or other piece of building material near a construction site around town. Or you’ve had a blowout on the interstate, or on a two-lane back road. Now what do you do?

While the answer depends on the specific situation, it also depends on what’s in your trunk. Do you know? And have you read the owner’s manual so that you know what to do with the various pieces of equipment the manual lists, assuming they’re all present and accounted for?

I’m betting that you might not know and that you’ve never checked. While the chance of getting a flat tire is fairly low – both tires and roads are better than they were when our parents learned to drive – it can still happen. Before you venture out again, why not pull out the manual and then dig into the trunk so you’ll be prepared if it happens to you.

But before we start, let’s make one thing very clear: In most cases, the driver should do very little when a tire goes flat. Slow down gradually while keeping the car traveling in a straight line, pull out of traffic and then continue to drive until you’re at a safe place to stop. Do not worry about further damaging the wheel or tire if you continue to drive; the safety of you and your passengers is primary.

If you are in a place that has good cell phone service or you have a newer Mercedes with “mbrace” services, stay in your car with your seat belt fastened and doors locked. Call the Mercedes 24-hour assistance hotline, 1.800.ForMercedes (1.800.367.6372) or push the SOS button for an mbrace emergency connection. Do not stand outside the vehicle or try to change the tire in high-speed traffic or on a dark and unfamiliar side street.

The operator who answers will send an emergency truck to change your tire or, if needed, tow you to the nearest Mercedes-Benz dealer for service. Most insurance companies offer towing assistance, and even if you don’t have Mercedes emergency assistance or are driving a non-Mercedes car, the Mercedes operator can still arrange for a service truck to respond, though you will have to pay for the assistance and tow.

But what if you’re in an area that is out of range of a cell phone tower – which generally means that your mbrace system won’t work either, as it relies on a cell tower connection? What then?

In this case, you may be on your own to fix the tire or replace the wheel and tire. This is the point where reading your owner’s manual and checking the equipment in your trunk ahead of time will become critically important.

When you look in a Mercedes trunk or cargo compartment, you will find one of four situations. If it’s an older model, there should be a spare tire and wheel of the same size and shape as the other tires and wheels on your car. On newer models you may have an inflated space-saver spare (like the spare in the 2013 GL350 pictured below left), a collapsed inflatable space-saver spare (equipped in the 2005 C55 AMG pictured below right), or no spare at all – the AdBlue tank occupies the space normally allocated to the spare tire and wheel in new diesel models.

If you have a standard tire and wheel or inflated space-saver spare, you’ll need to chock the wheel on the downhill end of the opposite side of the car, jack up the car, remove the flat tire using the lug wrench in the trunk, and replace the flat tire and wheel with the spare. If this is a space-saver spare, you will need to use the shorter lug bolts in the trunk in place of the car’s standard wheel lug bolts. Put the flat tire in the trunk, and you’re good to go. Take note: A space-saver spare is for emergency use only and can’t be driven safely above 50 mph.

If you have a collapsible space-saver, the only additional step is that you’ll need to inflate the tire to a safe pressure once the spare wheel is mounted. The tire will return to its small size when deflated.

If you have a flat on a car with no spare wheel (despite the run-flat tires with which these cars are equipped), the situation is more problematical. In the tool space, there should be an air compressor with a tank of fix-a-flat liquid. When operated, this gadget sprays expandable fluid into the tire that is supposed to plug the leak, and then the air compressor inflates the tire. The problem is that there are many kinds of tire failures that cannot always be repaired with this system. One solution: If you frequently drive out of cell phone range, consider purchasing an aftermarket space-saver spare that will fit your car and always carry it with you.

But please remember that all of these solutions are based on your knowing that every item needed for flat repair is actually in the trunk – and that you know what to do. Make now the time to find out – not when you’re surprised by a flat!
 
Top picture (featured) Under the floor in the trunk in Gary Anderson’s 2005 C55 is a collapsible space-saving spare mounted over a tool kit that includes an air compressor, gloves, jack, special lug bolts for the spare wheel, and a lug wrench, plus a bag of spare electrical fuses.

This picture: Under the cargo space floor in the 2013 GL350 BlueTEC diesel SUV is an inflated space-saving spare mounted under a tool kit that includes tow hook, gloves, jack, wheel chock, special lug bolts for the spare wheel, and a lug wrench. Safety vests are in the glove compartment.