MB Medic Mercedes-Benz Repair Guides, Service, How To DIY
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In this guide (8 sections)
Mercedes-Benz offers a Roadside Assistance program that allows customers to have a Mercedes-Benz representative travel to their location and help them with whatever roadside needs they may require. If you do not have the Mercedes-Benz Roadside Assistance program, however, knowing how to change a flat tire on your own is beneficial. Changing a flat on a Mercedes-Benz is easy; following these instructions will ensure you and your car are back on the road quickly.
Read this first. A car on a jack is the dangerous part, not the wheel.
- Get everyone out of the car and away from traffic. On a highway shoulder, people standing or sitting on the traffic side of a car are the real risk here, not the flat tire. Passengers belong behind the barrier. If you cannot get fully clear of the running lane, or it is dark and wet, calling for assistance is the better decision even if you know how to do this.
- Chock the diagonally opposite wheel. This is the step everybody skips and it matters more on a Mercedes than people realize: the parking brake works on the rear wheels, so if you are changing a rear wheel, the brake is holding the wheel you are about to lift off the ground. A wedge, a brick or a block of wood behind the opposite wheel is enough.
- Never put any part of yourself under the car. The jack in the trunk is for lifting a wheel clear, not for supporting a car you are working beneath. Nothing in this procedure requires you to go underneath.
- Only lift from the Mercedes jacking points. They are reinforced pads under the sill, usually marked by a notch or an arrow in the plastic. The sill anywhere else is a thin folded seam that will crumple, and on a car with air suspension you can do real damage lifting at the wrong place.
- Loosen the bolts before the wheel leaves the ground and tighten them after it is back down. A wheel that can spin cannot be undone or torqued properly, and pushing hard on a wrench is exactly how a car comes off a jack.
What you will need
Why a Mercedes is harder to do one handed than most cars
Worth knowing before you are kneeling in the dark wondering what you are doing wrong. Most Mercedes models use wheel BOLTS that thread into the hub, not nuts on protruding studs. So there is nothing sticking out to hang the wheel on while you line the holes up, and a road wheel is heavy enough that holding it level with one hand while starting a bolt with the other is genuinely awkward.
That is exactly what the wheel stud guide in the tool kit is for. It threads into one hole, gives you a pin to slide the wheel onto, and holds the wheel square while you start the real bolts. Use it. If your kit does not have one, they are cheap and worth buying before you need one rather than after.
Worth knowing before you are kneeling in the dark wondering what you are doing wrong. Most Mercedes models use wheel BOLTS that thread into the hub, not nuts on protruding studs. So there is nothing sticking out to hang the wheel on while you line the holes up, and a road wheel is heavy enough that holding it level with one hand while starting a bolt with the other is genuinely awkward.
That is exactly what the wheel stud guide in the tool kit is for. It threads into one hole, gives you a pin to slide the wheel onto, and holds the wheel square while you start the real bolts. Use it. If your kit does not have one, they are cheap and worth buying before you need one rather than after.
Instructions
- Park your car in a flat, dry place to jack the car up easier. Ensure your car is parked on the shoulder of the road in a safe and isolated spot to avoid oncoming traffic as much as possible.
- Move the shifter into Park, set the parking brake, turn on your hazard lights, and chock the wheel diagonally opposite the one you are changing.
- Open the trunk of the car. Lift the trunk floor, and you will find a Mercedes-Benz spare tire, a lug wrench, and a car jack.
- Using your lug wrench, loosen the lug nuts on the flat tire. Be sure not to remove the lug nut completely. Loosen them approximately one turn.
- Locate the jacking points on your Mercedes.
If you have trouble finding them, the Mercedes-Benz manual has guided pictures. - Raise the Mercedes-Benz just until the flat tire clears the ground, about an inch. Higher is not better. The further the car goes up, the less stable it is on a single jack.
- Assuming all lug nuts are loosened as described in step 4, use the lug wrench to remove all five lug nuts completely.
- Pull the wheel straight off and lower it to the ground. If it is stuck, rock it by hand from the top and bottom. Do not kick it and do not lean on the car, because anything that shoves a car sideways while it is on a jack is how the jack comes out.Â
- Place the spare tire on the wheel hub. Align the lug nut holes with the corresponding holes. In your spare tool kit, you may have a wheel stud guide like this one. Thread it into one of the lug nut holes. Â Now push the spare tire in and make sure it is seated properly against the brake rotor.
- Put the lug nuts on. Screw them in snug in a star pattern, firm but no more, so the spare is held square against the hub while you lower the car’s wheel assembly.
- Lower the Mercedes-Benz to the ground by cranking the jack counter-clockwise. Remove the jack from underneath the car.
- Once the car is on the ground, tighten in a star pattern: the top bolt first, then the one opposite it at the bottom, then across again. That pattern pulls the wheel squarely onto the hub instead of tilting it. Firm is the target here, not maximum, and the section below explains why that matters.
- Drive a few minutes and recheck them, then have them set with a torque wrench to your manual’s figure as soon as you can, and check them again after about fifty miles.
If you have trouble finding them, the Mercedes-Benz manual has guided pictures.
I can’t get the Mercedes tire off.
If the tire is not coming off, there are some quick fixes to remedy the situation.
- Try spraying WD-40 on the bolt heads and let it sit for at least 15 minutes. A dedicated penetrating oil works noticeably better than general purpose spray on seized fasteners, if you have the choice.
- Use a rubber mallet and lightly hit the inside part of the tire, not the rim, and break up the corrosion and built-up rust. Avoid using a metal mallet/hammer to dent or damage your car.
Can’t get Mercedes lug nuts loose
One problem Mercedes-Benz owners may face is that they can’t get the lug nuts loose. Over time, the lug nuts may corrode or refuse to come off. The lug nut wrench that Mercedes installs on these cars is inadequate to loosen these lug nuts and can bend easily. Here is a lug nut wrench that was bent when we tried to change a Mercedes-Benz tire.
To avoid this problem, consider using an aftermarket lug nut wrench that will not break and is extendable. For example, any Telescoping Lug Nut Wrench would be an excellent choice. It has four different socket sizes that you can use on any car. Most importantly, it can be extended, which makes getting Mercedes lug nuts a breeze.Before you drive away
Three things the spare changes about your car
- The space saver has a speed limit, and it is printed on the wheel. On Mercedes space savers it is usually 50 mph or 80 km/h. Read the one on your own wheel and stay under it. It is a narrower tire with a thinner sidewall carrying the same weight, and it is not built for highway speeds or for long distances.
- The tire pressure warning will come on, and that is expected. The spare either has no sensor or a sensor the car does not recognize, so the system reports a fault. Do not chase it while the spare is fitted. It needs resetting once the proper wheel goes back on, and on some models the system has to relearn rather than simply clear.
- Get the bolts torqued properly, soon. See below on why this matters more than it sounds.
Why “as tight as possible” is the wrong instruction
Overtightening is as dangerous as undertightening, and far more common
With a telescoping wrench and a bit of bodyweight you can put two or three times the specified torque into a wheel bolt. That is not extra safety. It stretches the bolt so it no longer holds correctly, it can distort the brake disc so you get a pulsation through the pedal, and it makes your next roadside flat genuinely impossible to undo with the wrench in the trunk.
Most Mercedes passenger cars sit somewhere in the region of 110 to 150 Nm, roughly 80 to 110 lb ft, depending on the model and the wheel. Vans and Sprinters are much higher. The figures published online disagree with each other, so take yours from your own owner’s manual rather than from a chart.
At the roadside, snug the bolts firmly in a star pattern and no more. Then have them set to the correct figure with a torque wrench as soon as you can, and retorque after about fifty miles, because the wheel seats as you drive.
With a telescoping wrench and a bit of bodyweight you can put two or three times the specified torque into a wheel bolt. That is not extra safety. It stretches the bolt so it no longer holds correctly, it can distort the brake disc so you get a pulsation through the pedal, and it makes your next roadside flat genuinely impossible to undo with the wrench in the trunk.
Most Mercedes passenger cars sit somewhere in the region of 110 to 150 Nm, roughly 80 to 110 lb ft, depending on the model and the wheel. Vans and Sprinters are much higher. The figures published online disagree with each other, so take yours from your own owner’s manual rather than from a chart.
At the roadside, snug the bolts firmly in a star pattern and no more. Then have them set to the correct figure with a torque wrench as soon as you can, and retorque after about fifty miles, because the wheel seats as you drive.
The thing to check in your driveway, not on the hard shoulder
A space saver sitting under the trunk floor loses pressure slowly for years, and the one morning you need it is when you find out. Check its pressure now. A space saver is normally inflated considerably higher than a road tire, and the figure is on the wheel.
While the trunk floor is up, check that the jack and the wrench are actually in there and that the wrench fits your wheel bolts, because cars that have been through a tire shop sometimes come back with different bolts. And if your car has no spare at all, which is the case on many later Mercedes with run flat tires, now is the time to find that out rather than at the roadside.
A space saver sitting under the trunk floor loses pressure slowly for years, and the one morning you need it is when you find out. Check its pressure now. A space saver is normally inflated considerably higher than a road tire, and the figure is on the wheel.
While the trunk floor is up, check that the jack and the wrench are actually in there and that the wrench fits your wheel bolts, because cars that have been through a tire shop sometimes come back with different bolts. And if your car has no spare at all, which is the case on many later Mercedes with run flat tires, now is the time to find that out rather than at the roadside.
Does a tire change need any diagnostics?
Not the change itself. The one thing it leaves behind is the tire pressure warning, which stays on after the proper wheel goes back on until the system is reset or relearned, and on several Mercedes models that is a menu procedure rather than a button.
If it will not clear, a tool that talks to the tire pressure system rather than only the engine will show you which sensor the car is unhappy about and run the reset. The YOUCANIC UCAN-II Pro reads the Mercedes control units and runs service routines like that one, covering nearly everything Xentry does apart from online VIN coding. For everything else on this page, hand tools are all you need.
Related reading
Before you buy parts, scan every control module, not just the engine. It shows the root fault behind the warning lights and tells you whether the problem is still active. See how to do a full health check.
