Hi everybody,

Just recently replaced my 2011 ML550 with a 2017 GLS550. Currently has Yokohama Ice Guards 265/50/20. Had to drive on a very bumpy and icy highway today (mostly ice covered, but bumps and chunks left over from snow plows) and nearly **** my pants. Was going about 60 (kph) (37 mph approx) and the car kept swaying side to side. It felt like it was driving in very strong crosswinds. At one point, it almost felt like the back was going to shoot sideways. I turned off all the assist features and put it in sport mode - that seemed to help a little bit. Once i got on snow covered roads, it seemed to drive fine, but I've had similar experiences with this car on dry roads as well, where it just doesn't seem to want to keep a straight line.

I guess my question is WTF is going on? My ML550 is like a tank on any road. Is this an issue of tires, it it an issue of the lane keeping system/assisted steering/assisted braking, or is the car just crap?

 

X166 GLS is far superior to W164 ML in every respect. If all active assists were turned off as you said, then the issue is with tires combined with the road conditions. (As a side note, I keep active lane "keeping" assist off, always).

 

Rear brake pads may also be sticking. Have the rear pins lubricated with a synthetic high temp grease. The stock return spring is weak and good lubrication is required so the pads retract.

 

Do you do that more so for stability/handling reasons or for what it may decrease the brake pad life?

 

Besides additional electronic safety features, your GLS has air springs + adjustable shocks. Not sure if that has anything to do with it, but off of the top of my head that's the largest difference between the two vehicles.

 

The former.

 

We just returned from Tahoe and saw a lot of vehicles sliding on icy roads (eg Tesla). Our GLS 450 did better than most with new Michelin Cross Climate tires. you had it easy compared to us as it is no fun being stuck in traffic watching cars slip in front of you on a hill and trying to brake on ice when you really need forward momentum to stay straight.

The simple truth is that everyone slips on ice. Driving slowly is the better course - 35mph is pretty fast and doesn’t give you much time to react and correct course.

 

I've found my 2018 GLS550 to be absolutely terrifying to drive in the most mild of winter conditions - conditions which other vehicles seem to handle just fine. First, it could not handle driving through 3" of slushy snow down my hilly street and I had to turn into the hillside to keep from running into my husband in his car in front of my (a 2018 Volvo XC90 which was creeping through the snow just fine). There was just no traction at all. Now, I realized after that, my tires were the terrible Conti UHP tires (though with only 10k miles), so I gave the GLS a pass for that.

We are right above the snow line and only only a few times a year - except for this year - do we get accumulations of snow that we need to drive in. 1,000' down the mountain, the snow hardly sticks around, and I do a ton of SoCal freeway driving so snow tires wouldn't make sense - snow tires are pretty uncommon on this little mountain given the infrequency of snow that stays around. So, I got new Yokohama Geolander tires. I also got chains. This last snowfall, I was heading down the mountain, with chains on, on streets that had been plowed but had a layer of frozen, icy snow just in parts - not covering the whole street. I used the hill descent button (which puts you at 4mph - pretty slow), and put in "slippery mode" and manual - it was doing ok, though at no time does it have the secure, grounded feel that the Volvo has. However, at one point on the mountain, gravity and loss of traction took over, and I started slipping several times. Meanwhile, at least four other vehicles passed me going down, none with chains or obvious snow tires. It was awful.

I'm not sure what more I can do aside from spend $10k to get narrower wheels than these horrible 21" things the vehicle came with. But even then, I'm not convinced that is the silver bullet that would solve the GLS's problem of feeling always on the verge of sliding out of control on any sort of wintry road conditions. This year in the CA mountains we've gotten way more snow than usual, but I am seriously thinking of selling the GLS because I feel so unsafe - particularly when other vehicles seemed to handle the conditions just fine.

 

What size are your tires/wheels?

I was originally looking for a GLS 450, but because I was looking at used vehicles I couldn't find one optioned enough, which is the main reason I went with the GLS550 (it had standard features like sun blinds and ventilated seats that were hard to find on a 450 - but I hadn't realized how much of a detriment it would be to have these 21" wheels - assuming that's the main culprit for the 550's horrible handling in winter conditions.)

 

We have 20” tires x4. I would not buy junk from Kumho, Yokohama etc. Michelin Cross Climate are the way to go if you want all season tires.

those people you see speeding by are foolish. All vehicles slip on ice. The only way to prevent accidents is to drive slow enough with enough space in front that you have time to stop. And try to time your pace so you don’t have to stop at an intersection when you are on a hill!

 

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There are so many conflicting thoughts with this reply so it would help to address some of them:

- Left out of the handling explanation between a Volvo and MB is what tires on the Volvo. It doesn't sound like the Volvo has the same performance level tires and suspect the may even be M+S rated for at least being somewhat effective in snow. Tire Rack.com in general shows the Continental UHP as a Street/Sport Truck Summer Tire which means they are NOT recommended for winter weather driving as well as having "N/A" for winter/snow survey stats. It's not reasonable to say the handling was awful when it's to be expected. No performance or summer tire does a good job in snow. The answer+ stay out of the snow with summer tires.

- "snow tires wouldn't make sense": Perhaps not in the true sense of "dedicated snow tires", but a M+S rated tire would be better than summer tires. "We are right above the snow line and only only a few times a year - except for this year..." So the answer is, for those exceptions= stay off the snow with summer performance tires.

- With family in California, I know certain areas and conditions have snow chain requirements which means even with dedicated ice/snow tires there are conditions that are a factor of nature which affect handling. This is NOT because of the brand of vehicle. It's understandable that different vehicles will handle differently yet people don't realistically stop to discuss vehicle weight, what their tire pressure affecting traction is, what their tires are rated for in ice and snow, and so on.

- Slippery Mode does not ensure or improve tire grip on the road surface by increasing the coefficient of friction.

- Even with summer tires, if they are not inflated properly, tire inflation is definitely going to affect handling.

- "I'm not sure what more I can do aside from spend $10k to get narrower wheels than these horrible 21" things the vehicle came with". It's a general understanding of what tires can and actually do
Blame anything but the vehicle in this case. 10K is not only unnecessary, it's still not going to solve driving too fast for conditions, nor will it take away from the need for proper tires and the proper air pressure, or tires with a suitable light/heavy snow & ice rating. People I know with performance cars have tires with similar characteristics as the Continental UHP and they do not take those tires out in the snow and expect safe handling.

- Research tires on websites such as tirerack.com and simply change the tires for $1K-$2K and sell the Continental tires. Otherwise, please don't endanger your life or the lives of others by expecting tires alone to keep you safe. The laws of physics are at work, and even a highly rated ice/snow tire such as the Bridgestone Blizzak are not going to make a vehicle always handle like it does on dry pavement.

 

Thanks for your thoughts, John. However, maybe you missed it in my post but the first thing I did after my initial experience was change the Contis to the Geolander X-CV which are M+S tires and seemed (after pretty exhaustive research) to get decent reviews for this sized tire. I was hoping to have a better experience, especially using chains (on the rear tires, as required by MB). I also was proceeding very slowly down the mountain to avoid needing to brake. Yet even then 1) other vehicles were passing me, which is fine but indicated that their vehicles were handling the conditions better and 2) I still was sliding. From my limited experience, even with brand-new M+S tires and chains, along with very conservative driving (I grew up driving RWD in New England), this vehicle seems to be at some disadvantage on roads like this.

I realize that wheels/tires are the logical answer, but the GLS550 wasn't optioned with different wheels that I'm aware of, the dealer was of no help in trying to inquire and was the one who mentioned $10k for aftermarket changes. I actually solicited the hive mind for recommendations on practical wheels/tires (which I appreciated, as it confirmed one reasonable option being the Geolanders). But of course another response I received was, to paraphrase, this was the wrong car for my type of docile mountain driving and that it's a powerful beast for dry pavement. Sure, but I don't think it's unreasonable to expect that it handle a very modest winter road with new M+S tires, chains, and conservative driving - but it appeared to be the poorest vehicle on the road going down the mountain that day. If that's the concession required for driving this without aftermarket wheel mods (or if it absolutely requires snow tires each year for the most minimal amount of snow) then that is something to take into account I suppose. And if that's the case, then perhaps it isn't the car for me or others who don't want to be worried about storing/installing snow tires just to get through minimal amounts of snow each year without dangerously sliding.

This is not a rant at you, of course, and I do appreciate your thoughtful response; I am just supremely disappointed in what I consider to be subpar performance of a pretty basic nature.

 

Beemie, is your XC90 equipped with 19" wheels or 20"/21"?

 

I can't believe the 550 is much different from the 450 in the handling department. We also had an XC90, and hail from New England. I wouldn't say the GLS is any less capable than the XC90, much less call the GLS unacceptable. (I haven't resorted to chains on a passenger car since the Blizzard of 1978.)

I think if I were in your position I'd find the best alignment shop I could and ask them to take a look at it. You want someone who knows what adjustments have what effects, not someone who knows how to change things to make the needles line up on the machine.

 

keep active lane "keeping" assist off, always).

 

The Volvo XC90 has 20" wheels (275/45-20 - specifically Pirelli Scorpion Verde AS Plus II, which are M+S). When we bought the car new in 2018, we actually insisted, as part of the deal, on "downgrading" from the 21" wheels that came with the T6 Inscription, but that Volvo was technically optioned with either 21" or 20".

The GLS 550 as you probably know was only offered with 21" wheels. I just had no idea how big of a difference that would make in wintry conditions. So I now have 295/45-21 wheels that are now all Yokohama Geolander X-CV (M+S). If there was a ready option to swap wheels for something smaller/narrower, I would definitely consider it. But since there doesn't seem to be an "off-the-shelf" option, it's a daunting research project for me. I find it less daunting to think about switching vehicles to something whose standard configuration simply works vs "modding" something at significant cost to achieve a basic level of suitability.

 

Thanks for that thought - I have thought about going to my pretty reputable indy MB shop to adjust the alignment to address the rear toe/camber to be the least exaggerated as possible (within spec) since at 10k miles the inside of the rear tires were extremely worn compared to the outside (thanks to info gleaned on this forum). I will add that to the agenda.

Blizzard of '78 - my parents lived down the Cape at that time and ate a ton of washed up lobster (not sure if it was the blizzard or a later flood) and I was born addicted to lobster a few months later. And I never once used chains in Mass. either.

 

Bemmie, I would install a second set of narrower (8.5" or 9" wide) 20" wheels with 265/50 or even 255/55 more snow/ice dedicated (those with "severe snow service rated" logo instead of currently installed "touring" tires even though they do have a very deep for "touring" tires thread depth) for your "winter" season period. It will make all the difference (along with disconnecting "lane keeping assist").

 

Comparing the Volvo to the 550 is a tough thing. Tires are about the same width, however the AWD systems are not and the 550 puts out 515ish lbft of torque whereas the xc90 puts out 300ish. The 550 was designed as a performance vehicle so all that extra torque goes to the traction-less wheels (even in snow mode where the torque curve is reduced) causing slippage. The XC90 is Front wheel bias (up to 60/40 split) where the 550 is rear (up to 50/50 split). Using the front steering wheels will pull you through those slippery curves instead of pushing and because the XC90 will have at most 60% of the torque up front, the handling characteristics wont change. I think the best you can do is get as narrow a tire as possible and probably a dedicated winter tire/rim set.

 

There is more than one factor at work here. If you ever tried to roll a tire (or a hoop) you know that if you tilt it to one side it will steer to that side. Cambered tires do exactly the same thing; negative camber makes them try to steer toward the center of the car, so a certain amount of toe-out is required to make them track straight and wear evenly. If it is set wrong, or unevenly side to side, the tire(s) will tend to "plow" and steer the car off course. If the tires are tending to steer the car, and one tire looses traction, the opposite tire will push the car off course.

Another factor is the overall weight of the car. Combine a heavy load with incorrect alignment and you get accelerated wear and unpredictable handling.

With chains on the rear the car should track straight. It may not steer, but it should track straight!

Were they metal chains?

 

Good point. My understanding from other threads here (like this one) is that MB specifies what has been called "excessive" negative camber, but makes sense that would contribute to worse handling when traction to one of the wheels is decreased. I was using metal cable chains - cheap $150 ones, admittedly, because I was hoping to avoid spending $700 on the beefier Konigs for this wheel size before considering all options and feasibility of new wheels.

This is a great explanation and makes a lot of sense - thank you. I do like the 550 and perhaps finding new wheels/tires will be easier than beginning a car search for a new/used car that meets my long list of must-haves options.

Thank you. So are these tires something I should ask my indy MB shop to help source, along with adjusting the alignment specs for less negative camber? Or should I query some high-end custom wheel shop? Or other suggestions on who would be an "expert" who can assess suitability given brake clearance needs, etc? When I look on tirerack for tires/wheels, they of course don't offer any option other than the 21" wide tires specified for the 550. And my small local tire shop if fine for installing/rotating but they definitely don't think outside the box, so I wouldn't rely on them (and my inquiry with the dealer suggests they also won't think outside the box to consider wheel/tire recommendations that aren't factory options - so if anyone has recs in the greater LA area - from the Valley to OC - I'm all ears!)

Really appreciate all of your thoughtful responses here (and sorry to the OP that I highjacked your thread but hopefully it is helpful for you and others).

 

I have dealt with The Tire Rack for over two decades. They are VERY conservative in their published fitments. If you call and ask for Luke at extension 362, you may get more than there is on their website. Just FYI: even some 19" wheels will fit your car (specifically 19x8.5 or 19x9 with ET of 30-40), the biggest issue is finding the wheels with proper carrying load certification. Tire Rack has all this info on all wheels they sell. Also, it is important to go beyond your specific model and year to search, for X166 GLS one might also look at X166 GLS450 and X166 GL450/550.

So I did some digging and found the following in 20":

Tires: (the easy part) - I would look into Vredestein's Wintrac Pro Performance Winter tire in size 255/55-20 or 265/50-20 (BTW your OEM size should be 295/40-21 not 295/45-21 posted above) IF you are able to find a suitable 20" wheel not wider than 9".

Wheels: (this IS the difficult part)
option 1 is 20x9.5 MSW Type 48 (excellent quality and beautiful rim too), but it is not in stock now(expected by end of the month) and may require small front spacers because this wheel is listed for X166 GL450, but Luke would know for sure if this wheel with et52 clears 275mm front rotors and the calipers of your car. The issue with 9.5" wide wheels is that wider tires (275/50-20, but still much better than 295 section A/S) are required which negates somewhat what you're trying to accomplish;
option 2 is to ask Luke if they have 20x8.5 or 20x9 wheels with carrying load rated for your car (there maybe some that are not listed on their web)
option 3 (be careful here) is eBay looking for "replica" 20x8.5 or 20x9 wheels advertised specifically for X166 GL/GLS.

 

ThreeMBs, thank you so much for taking the time to dig around and share these options, along with the referral to Luke - this was very generous and is incredibly helpful to me as a starting point. I will reach out to Luke as well since it sounds like he is attuned to the specific issues and requirements of the car. But it sounds like there may actually be options out there for an appropriate winter tire (and if the wheel fits, maybe I could switch tires but keep a 20" wheel for the rest of the year? I like the idea of more rubber for potholes and bumpy roads...). As far as rated carrying load, am I correct in understanding this is only looking at the GVWR of the vehicle, but doesn't necessarily take into account something like towing? (I tow a lightweight, Euro-style horse trailer pretty regularly - total weight with trailer, horse, hay, water, etc. is less than 4,000#).

 

I would assume that snow chains are used because of extreme conditions, so one would want to be on the narrowest tires possible hence the narrowest wheels possible.
Now on dry summer roads the opposite is true - wider tires are preferred hence requirement for wider rims.
So personally I would not compromise to stay with a singe 20" wheel choice.
An other possibility, one I would look into seriously if one can "live" with their look, is getting pre-owned OEM (or replica) X166 GL450/GLS450 20x8.5 (or even 19x8.5) wheels with narrow winter tires and use quality 25mm DRA spacers (like H&R's p/n 50556659) to clear calipers due to OEM 20"/19" wheels' high offset of et62.

 

Hey op, never put the car in sport mode when roads are slick .... there's a slippery mode option, that essentially minimizes sudden acceleration..., also for traction in snow you need dedicated winter tires, these are german cars and in Germany its mandatory to have winter tires in those seasons... I know we like all seasons but the car isn't designed like that ... my personal experience has been great with winter tires, but completely opposite with all seasons in the snow and icy conditions especially in hills.