danmiles68

Hello,

I bought a preowned 2015 S550 4Matic 30 days ago, which replaced my 2014 CLS550. The car only has 38k miles on it, but I have noticed that the car has a very bumpy ride when going over potholes or just on rough pavement. It came with 19" AMG wheels and run-flat tires. I have never had run-flat tires, but many have complained in other forums about the ride from run-flat tires, but I can't imagine that they would cause such a noisy and bumpy ride over potholes. Any thoughts on what issues might be going on? The vehicle doesn't drop at any wheel when sitting, so I assume there is no leak in the AirMatic system, but I could be wrong.

Thanks in advance!

Tom in Austin

Congrats on the new S and welcome to the W222 forum. A couple of obvious things to start with:

1. Is the suspension in Sport or Comfort mode?
2. What is the tire pressure? (Recommended settings are on the fuel filler door, one for regular driving, and a higher one for "extra load")
3. How old are the tires, generally ride comfort declines as tires age and approach the end of tread life. The brand and model of tires are factors too as many on here have found some are much stiffer riding than others

Everyone's standards/expectations are different, but an S is capable of a very nice ride on good, fair or slightly bumpy pavement. On truly rough roads, over railroad tracks, etc. an S can jolt and shake hard at times, at least according to my 'assometer'.

danmiles68

Hi Tom, thanks for the reply. It doesn’t matter if the car is in comfort mode or sport mode, the ride is still the same. Tire pressure is a couple of psi‘s below normal but I wouldn’t think that would make a big difference. Tires are Pirelli Cinturato P7 and appear to be relatively new with very good tread depth.

emilner

Based on what you said it sounds like a suspension (possibly airmatic) issue. There is a noticeable difference from sport to comfort. Comfort should feel smooth even on older RFTs.

danmiles68

I guess I need to take it to the dealer, I just hate getting hammered by their prices. I need to find a good Indie shop that knows these cars.

cfmistry

Runflats are likely responsible for your bumpy ride. Unless your car is sitting very low, its unlikely the Airmatic is the problem; their only typical problem is deflation. As for the noise, that may be specific to your tire, or you have have been expecting more quietness than the S-class actually delivers (this was an issue for me as well).

emilner

A runflat will not cause a "bumpy" ride. They just get harsh over jolts. If you are driving and the ride is up and down bumpy that has nothing to do with tires. I have heard of issues with the suspension where it firms up dramatically...

cfmistry

He stated he had a "very bumpy ride when going over potholes or just on rough pavement". In my humble and lowly opinion, that is likely from the RFs. I suppose it could not hurt to have the Airmatic system checked, but I know where I would put my money!

danmiles68

It’s almost like riding in the back of a beat up Uber or taxi cab when I drive over bumps in the road. Even my CLS was smoother although it was a sporty and rougher ride than previous E and S class cars I have had.

danmiles68

I guess I will look at replacing the tires. Even if the AirMatic needs some work, I have not heard of anyone who likes runflat tires.

SW20S

When you say the tires are a few PSI below normal, what PSI are they cold exactly?

I have non runflats and I run mine at 32 PSI Cold and it rides great on AMG 19s.

Donnymac

Road surface imperfections will be magnified with a RFT because of the rigid sidewall design. A NRFT will deliver the opposite result due to a designed flexible sidewall.

The two do not ride the same.

danmiles68

The pressure is between 35-36 psi cold.

Tom in Austin

Normal tire pressure spec for my car is 33 cold for 19 or 20 inch tires

Streamliner

For those of us that are highly critical of ride quality, run flat tires are the KISS OF DEATH! Admittedly, RFT have improved over the years, but when switching to a non-run flat, very cushy, all season tire, the difference, at least to me is DAY AND NIGHT! I run 18” wheels with Bridgestone QuietTrack tires and MBC on my 2020 S560. I believe my car is the best riding, most quiet sedan this side of a new Rolls-Royce. I carry a W221 compact spare in my trunk. Good luck to you.

DaveW68

I concur with others here that RFT's suck and ride like crap. They are also prone to having the tread split from the sidewall when hitting potholes or large bumps in the road. Basically, they're garbage and don't belong on such fine cars.

I've got the AMG 20" wheels and swapped out to these tires in the spring. They've been fantastic and ride super quiet and smooth, even on 20's. They'll also save you a ton of money over the Michelin's and are every bit as good.

No need for a spare in your car when not having RFT's. Blow-outs with regular tires are extremely rare....kinda like the odds of getting hit by lightning. And slow leaks from nails or whatnot can easily be repaired before the tires get too low. But if you're on a trip and notice a faster leak, you can always have this in your trunk to take care of those instances.

Streamliner

Unless, of course, you happen to hit a road hazard that shreds the tire and/or destroys the wheel. As a former Boy Scout, I always believe in being prepared.

DaveW68

WE ARE PREPARED!!

The trunks in these cars are smallish for a large car. And yours is even smaller with the rear sub. The spare cuts in to the space too much and is completely unnecessary. In 37 years of driving, I've never had a blow-out and I bet over 95% of all drivers on the road have never had one either. But if you do get struck by lightning and have one, that's what AAA, your car's insurance, or your car warranty is for to cover a tow. And please don't reply about a long weekend trip or tire repair shops being closed on Sundays. Those donuts are only good for 50 miles and won't help you finish your trip without a stopover anyway.

SW20S

I would lower it to 32 and see what you think.

Streamliner

TRUE STORY: Around 1998 or so, I was driving my 1997 Lexus LS400 home from my office in the L.A. area to my home in Orange County, on the infamous 405 San Diego Freeway, passing through Long Beach. It was later rush hour, around 6:30pm or so, dark outside and traffic was heavy, but moving fast. I was in the fast lane, doing around 65 or 70mph, when my right front tire hit something and the tire blew out. I managed to control the car and get to the right shoulder, where I called AAA. Before they came, a Metro tow truck, pulled up behind me, lights ablaze. The driver jacked up the car, put my FULL SIZE, MATCHING spare on (Thank you, Lexus!), put my chewed up wheel and SHREDDED, nearly new Michelin tire in the trunk and I was home for dinner. I never knew what I had hit, but the tire was destroyed, and the alloy wheel needed to be replaced.

Had I been driving most any car, with most any type of tires and no spare, I would have been riding in the cab of the tow truck, leaving my car overnight somewhere and taking a taxi home. Now, just imagine this exact same scenario, but the car is full of your wife & kids and you are not in a metro area. Not good.

SW20S

But that was 23 years ago and hasnt happened since. Its a hassle/benefit analysis as to how much you want to sacrifice to prepare for something that might happen once in a persons entire life...

badq45t

I would give up the one incident for giving up all my trunk space. My S550e has even less than standard so when I switch I will add a pump and some fix-a-flat (last resort) and my AAA Premium subscription will cover me trom there. To the poster, the S Class shouldn't be a bad ride, I haven't heard good things about the Pirelli's and you should go to America's/Discount Tire or a place that will give you a trade-in credit since you mentioned that the tires are nearly new and get a set of non-run flats.

Streamliner

You make a good point. We all have choices to make. I choose to carry that spare. It gives me peace of mind and with just my wife and I, we have never needed more trunk space, so I really don’t feel as though I am giving anything up.

Donnymac

One size does not fit all. What is sacrifice to one is insurance to another. Also depends on where and how you drive. My S has a trunk with a backpack, bedroll, rifles, cutters plus a satellite phone and it survives the car wash just fine. AAA is of no use to me and I need a spare. I get the RFT concept but I’ll take the insurance.

DaveW68

You and your wife must not be golfers. I have the reclining rear seats like you, so I too have the notch in the front of the trunk. I also don't have the rear sub. But my golf clubs still barely fit on an angle with shoving the woods and irons into that front notch. With a donut spare, the only clubs that would fit would be little kids clubs.

I choose to carry golf clubs at all times. It gives me peace of mind.