poor handling on grooved payments
 

When driving on grooved pavement, my 2012 ML350 swerves back and forth on the road. It is a very annoying and uncomfortable ride. Does anyone else have this problem? Any ideas what causes this? My dealer checked the alignment and says it is in spec. I have actually had passengers in the back seat get car sick from it! Please help.

It's a road issue. You're not the only one on that road to have that issue. Certain tires act funny on certain roads too

I notice that my new W166 (Pirelli tires & Airmatic suspension) does this noticeably more over the same roads than my previous W166 (Continental tires & spring suspension). It's a pretty significant difference.

Check your tire pressures - most dealers inflate 40-42 lbs - Mercedes recommended is about 36 if I recall correctly - adjust down by 2 lbs from wherre you are at now - drive that for a week/10-days, then consider further adjustment from there.

Keep the beat !

I've had all three generations of the Ml and only had that problem on grooved roads. Usually the groves were caused from road preparation for resurfacing or grooving to aid in rain runoff. The swerving was never bad but was noticeable enough. If the tires are up around 41ish let a few pounds out as mentioned above. Also, if you have the airmatic check to see that the setting is not in "sport" mode. That will soften the ride a little too.

Thanks for all of the suggestions. Keep 'em coming. I did drop my tire pressure, and it seemed to help slightly, but the problem is still pretty severe. I had the problem with my original Continental tires, but it is worse with the Michelins I have on the vehicle now. The worst part is that I regularly drive a 30 mile stretch of freeway that was resurfaced last year and is grooved the whole way. Not a pleasant driving experience.

My 1st ML (with Continental / springs) is set at 40 psi; the new one (Pirelli / air) is set at 35 psi and is the bad one.

You might want to check your alignment.

At 35 psi - you might crank up 3 psi to 38 or so and see if the difference to your drive feel is positive for you for a week/10 days - you should notice a "difference" - if not to your liking - then crank back down to 36 and call it a day..

Ditto!
Your probably experiencing tramlining. The larger the wheel (shorter tire sidewall), the wider the tire (usually summer rated high performance tires) and tire pressure all have effect on tramlining. Lowering the tire pressure is the best way for improving the ride. Some brands of tires are more susceptible to tramlining than others. I lowered my air pressure to 35 PSI (from the 40 set by dealer) and it has helped some.

I have not personally experienced this, but could it be the "lane tracking assist" picking up the grooves? Try turning it off to see if it makes a difference.

I have noticed this picking up the joints in hotmix bitumen.

I experienced this on my current ML350 Bluetec on grooved highways around metro detroit along with my older 2010 ML350, 2011 BMW 5, and 2013 Lexus GS350 F-sport. Its not uncommon but is annoying on some sections of the grooved highways. Dropping the pressure on the ML to 33 psi cold was perfect for this car and minimized this sway a bit. There is NOTHING else we can do. I HATE grooved highways as they are noisy, rougher, etc. I have noticed it on my current Pirellis and Michelins. Not so as much with continental tires.

Its called tram lining. The tire treads follow the grooves in the road. Runflats are really bad about doing that. It has to do with the type of tires as well. BMW's are really bad about it due to using runflats almost exclusively. My GL 350 bluetec has runflats and tends to tramline at times but not as bad as my Z4 that I no longer own. Sometimes its just the road conditions. Irritating non the less.

I agree with what Robalo said. It has little to do with the way the car is set up as to alignment and suspension. Mostly, it has to do with the tires - their tread pattern and secondly, tire pressure. Even experimenting with different tires and different air pressures will not totally eliminate the problem as that is the nature of grooved payments, but it should make it better.

Something else I have considered: newer tires could seem worse than those with more wear, since the treads are fresher and more likely to bite into the highway grooves.