Tire Pressure Warning
 

My 2011 GLK 350 gave me a tire pressure warning "check soon" message last night returning home from the airport. I drove the 100 km back home without any issue but this morning the same message appeared in red (my screen is white on black normally). Knowing I was heading out again to pick up some one at the airport tomorrow, decided to check with my dealership who found 2 finishing nails embedded in the back right tire. It was supposed to be 37PSI and was 18PSI for many be weeks...who knows. So as it dis not indicated which wheel was having an issue, how would you have solved this? And why indicate a problem with half the pressure lost already ? I suppose the tire would have separated from the rims eventually if I had continued.

Our other MB tells us which wheel is under inflated or damaged.

Or, now that the vehicle has alerted you to a very specific problem, you could use a tire pressure gauge and measure the pressure in each tire.

You set the warning pressure on the service screen. You could have looked at the screen anytime but especially watched it when the warning came on. Someone must have set it very low if you got down to 18 psi.

Canadian GLK's don't have TPMS so the tire pressures are not shown on screen. The system uses the ABS to compare the rotation rate of the tires to determine if one is lower than others.

Sorry thought it had TPMS. I know on the Fords that use to use the comparative rotation type system, there was a method to zero the compare system after tire replacement, but it could not tell the actual pressure. It assumed that a tire rotating faster by a certain percentage was losing air. With run flats, I guess it is not quite as important to know the actual pressure.

Once the correct tire pressures have been set with an external gauge, you can "zero" - restart with current values as reference - the system that uses the ABS sensors. It won't detect a small leak, but will trip once one tire pressure drops some ~10 psi below the rest.

And, in this case they're probably not run-flats. It's a Canadian car.

To the OP - may I suggest that you invest in a $10 tire pressure gauge in case you're unable to visually notice a 19 psi drop in a tire? This is what it looks like:

https://cimg2.ibsrv.net/gimg/www.mbw...1d29442685.jpg

Well after a second day of warnings the dealership discovered 2 finishing nails embedded in the rear passenger side tire.They were the cause for a very slow leakage. the tire was permanently patched and the system reset. I appreciate the great responses and was a bit shocked that there are no TPMS in Canada. I guess we just are not all that special after all.

Appreciate the feedback but if you were to have seen the tire it never looked this flat. It was easy to take a visual inspection and not know which tire was
affected.

I hear you. I've spent over 15 years tracking various cars and on the track a 2 psi change makes all the difference in the world, so on the street I can probably detect a 5 psi drop in any one tire (OK, maybe 10 psi in the GLK if it's on the rear and I am just cruising in a straight line) just by the way a car feels and sounds (tire noise). That is certainly not the norm nor the expectation though, so a cheap tire pressure gauge will tell you which tire is the culprit, and the MB compressor & sealant kit (you don't have TPMS sensors to worry about) is usually all you'll need to get you to a service station safely. :y

I certainly would prefer to have the TPMS system. Likely the Canadian versions are like this to save money.

But make up for it with default extra anti-rust protection, all-season tires (not Quebec where winter tires are the law for 3 months), 4-Matic only offered and a few other cold weather requirements. Yup, it would be nice as I consider tire pressure a safety feature not an option but MB Canada thinks otherwise.:smash:

Like many things, the U.S. government mandated the whole tire pressure display warning thing (in 2010?). Added complexity, increased cost and helps encourage drivers to not use their brain and to not check things themselves. Not saying it's a horrible thing but where does it end?? Why are we so stupid (and maybe in Canada??) that we have to be TOLD that objects in the mirror may be closer than they appear? How have all the primitive people in other countries (I assume they can't read anyway) survived, to date, without regular fatal accidents? It's luck I tell you!

https://cimg5.ibsrv.net/gimg/www.mbw...b3ed3b6d06.gif


:y:y

as a side topic, so any Canadian GLK doesn't require the TPMS when it's changed to the winter tire on?

Hope this is not a hijack, but there are some knowledgeable folks on this thread.

I have a 2015 GLK350 (USA spec) and I am going to do my own tire rotation every 5k miles as I disagree with MB that they can go 10k before rotating. Been doing this over 40 years on hundreds of cars, yadayada.

Do I need to RESET the TPMS after the rotation? In other words, are the sensors specific to each corner? Or can I just rotate, set my preferred pressures & good to go.

Thanks.

Mod can move this if I need to start a new thread.

:)

FWIW I wish the feds had kept their nose out of my tire pressure decisions.

That is correct.

No need. It resets and reads itself.

+1 on both of the above.


Interestingly enough - the TPMS system on my C63 which uses the same discrete TPMS sensors as the US GLKs somehow managed to swap the left and right wheels. I was gettign a low pressure warning on one wheel and after repeated checks with an external gauge decided that the sensor had gone bad - until I checked all four tires and realized that the one on the opposite side of the car is the culprit. Sure enough, I could see the pressure reading in the instrument cluster go up as I was inflating the opposite wheel. This happened after I took the street wheels off for a HPDE event and then put them back on on the opposite side of the car. It has never happened before or since - I am now on my winters and they were picked up properly after a rotation from last year - but I thought I'd bring it up just in case you do get a warning and go to the corresponding tire only to find out that it's not low. Check the rest as well.

That's something of a good argument to have simpler systems that simply tell you something like "Check Tire Pressure." Might get more people out there to check all their tires.

As an aside, I'm still wanting to check the pressure on my spare tire twice a year in the GLK. Need to break that habit for obvious reasons...

Not sure but the 2014 GLK 350 came with inflatable donut. No tpms there.

Right. I probably wasn't clear. I'm used to checking the spare tire on previous cars I've owned. They had "real" spares. Never had one with a spare in a normally deflated state, until the GLK.

2015 same deflated donut.

The deflated donuts are there to save space and are perfectly workable, with the only downside being that they take a while to inflate with the portable compressor - but if you start inflating it before you jack up the car, it will be fully inflated by the time you're ready to bolt it on. Porsche has been using them for the last 35 years without issues.

Besides, I'd actually look at them as a safety feature - as MBKLUE juat pointed out, when was the last time you checked your pre-inflated donut "real" spare for correct tire pressure (~60 psi or whatever those things usually take)?

Good idea to start inflating before starting with the jack. In the confusion of fixing a flat i would not have thought ahead like that. thanks.

I actually inflated the donut and it didn't take long when I had the flat. It has an unusual shape when inflating and deflating that you would think it was deformed.