Lodi

I was driving my 2019 GLS 550 with a mileage of 16500, couple days ago on the highway way, with cruise control around 70 mile/hour, same as the speed limit. Suddenly, the heavy rain started. I felt the car was trying to brake down by itself for seconds, then the car started to spin and slid off the road into the ditch between the high ways. I got back to the high way and drove the car at 60 miles per hour in the rain without cruise control only for couple of miles before the car spun again in the same way as before, and slid off the road. Thanks to God, the car and me were okay except some scratches and tears to the back of the car.

I have driven different cars for more than 20 years for about 200k miles without any accidents. I drove in heavy rain or snow before, but nothing like this happened. What’s wrong with this car? Please help me with your thoughts and suggestions.

Thank you very much and have a nice evening.

skim7x

What tires are you on?

Lodi

The tire is 295/40 R21

skim7x

What brand, though? Are they the original tyres?

Lodi

The brand is Confidential, the original tires.

Scorpio550

yeah i am experiencing the same with my 2017 GLS550 the car has no traction in heavy rain, same issues had with the 2015 GL550

Lodi

This is the problem only for GLS 550 or also happens to other large SUV?

jbattan

The obvious and only question is: what is your tread depth? Trying to drive on rain with slick tires is a fool’s errand.

pdeacon

This sounds strange. Yes, tread depth is important as is tire pressure. But how bad can the tires be at 16,000 miles? Check anyway. The other issue, and I know you stated that this occurred with cruise on and again with cruise off, you should never use cruise control in any type of inclement weather...like rain or snow or wet roads. That's looking for trouble. Just curious...was your lane departure system engaged?

ygmn

Probably hydro planing.
If tire contact patch is huge this can happen more oftgen then not.
Based on tire size you posted that is realy wide patch and tire OD.
.
11.6" wide by just over 30"OD
Check your air pressure is to spec

Maybe get better wet weather tires...

ksalno

I drove a 2010 GL350 for 10 years on the Goodyear run-flats (OEM tires) and never had any issues with rain or snow. In fact, in snow, I was often able to go when others in AWD couldn't. I drove in lots of heavy rain with no issues. If your vehicle is spinning out of control your tires are shot and/or you're going too fast for conditions. I would never use cruise control in bad weather. I only have a few hundred miles on my GLS580, so can't really comment much on how it does in bad weather but don't expect it to be any worse, especially with all the new tech on the GLS that didn't exist on my GL.

Lodi

It sounds terrible. What do you do with your GLS 550 if you run into heavy rains now?

Lodi

I check the trades, which looks good to both front tires, but quite bad to the back tires especially the one to the left back. My next maintenance is due in August. During my last maintenance and also the first one, I was told everything was fine. Why are the back tires worn out so badly for such a mileage?

Lodi

I usually keep the tire pressure about 40-42, which was on when I got the new car from my dealer. According to the tire pressure list on the fuel lid, 40-42 are little bit higher.

Yes, the lane departure warning system was on for the both times. Actually, my first thought was that somethings went wrong with the system. I felt the system was overreacting and trying to brake too much and cause the car to lose the control. Do you agree with that?

Thank you all so very much for your educated comments.

Lodi

Thank you very much.

ygmn

There is your problem worn rear tires.

They wear fast since they are SPORT high dry traction tires probably which means they do not last very long

Lodi

I never had the problems before with other cars, including Honda Accord, Pilot, MB E350 for more than 20 years. This is my first car with these Hi-techniques which make me scared now.

Lodi

Is it possible something wrong with the wheel alignment to wear rear tress fast? I was impressed the front tires wears out faster usually.

wyatt88

Lodi, I am wondering if your car's lane departure assist may have been inappropriately applying the brakes, causing your car to lose control. I know the lane keeping assist will jolt my car when I drift in a lane. Fortunately I have not experienced this while driving on slippery wet roads yet, but have wondered what the effect of that 'sudden jerking' would have if driving on snow or rain.

Also with rain the lane keeping assist may have difficulty sensing the actual lane markers, applying the brakes when not needed.

jbattan

So yes, get an alignment when you replace the tires. And don’t be surprised if you have to replace the rear brake pads much more often than the fronts, which is counterintuitive.

bad habit

I would also check alignment as well as tire pressure. One more thing: if you used on of those tire dressing products, it can make your tires very slick.

marchgroupinc

How are the tires worn, evenly across tread? more in the middle? at one or both edges? If they are worn in the middle primarily your tire pressure is too high. 42 sounds like the pressure for full load. My GLS580 tire pressure for normal load is 29 lbs.

marchgroupinc

35 Front 36 Rear is what I read is on the gas filler lid for a 2017 model GLS550 - I don't know what options so your's could be different. What does it say on your gas filler lid? You should follow what is on the gas filler lid unless you are hauling a big load like a heavy trailer or 7 adults with luggage, otherwise you will get premature tire wear and a harsher ride. I don't know why Mercedes makes the door jamb tire pressures different than the gas filler lid but the gas filler lid is what you should go by. If you are not fully loaded most of the time use the lower tire pressure.

Lodi

This was my first thought after the accidents. I still believe that now it’s the overarching or disfunction of the lane departure warning system contributed majorly to, if not absolutely caused the accidents. I already deactivated the system.

Should we let MB know about our suspicions and let them check it?

Lodi

I called my dealer and made an appointment for multiple points check as well as wheels alignment.

Thanks a lot.