np888

According to C&D, the CLS 550, which is 500lbs heavier than the E550 coupe, will do 0-60 in 4.2s.....is our car a sub 4 second car then?

Dueclaws

Don't know what the 0-60 time is for this car:
"I just had a friend do his e550 4 matic 2012 RENNtech ECU tune only at the track 12.528 at 111 mph"
Found this post in the Tuning forum.

mambrose23

Our cars are quite traction limited. Even with 275/30/19 Michelin Pilot Sport rears, I can't floor it from a start (not something I'd want to do more than a few times anyway) without getting wheelspin, and lost time. I'd figure low to mid 4's is more accurate, but who knows. I did play around against a 2012 CLS 550 from about 20 mph and felt I was at least his equal. We didn't go for long though as we were on a public freeway.

ronsc1985

Drag Strip times are meaningless unless you know the weather conditions and the track starting line prep. Temperature and barometric pressure can easily vary horsepower 10% in the normal range at sea level of 60-100 F and 29.8-30.4 psig barometric pressure.

Starting line prep is another story altogether. If you go on a street car test and tune night the starting line will be torn up almost immediately from people using street tires.

If you want to get a decent starting line prep enter a weekly race for race cars on slicks. You will get beaten first round but you can get a better indication of car performance without excessive wheel spin off the line.

Dueclaws

Good info: thanks

Shifter

was the cls a 4 matic model? That would help big time , as the coupe is traction limited

np888

Really? I was thinking about swapping out the pathetic 255 primacy tires for some 275 PSS, but if there's no real improvement I won't bother. I'm still in awe at the stupidity of the decision to put 255 primacys on a car with 440lb-ft of torque.

threeMBs

Replacing stock A/S 255 tires by sticky/summer (like Michelin PS) 275 is a must. Keep in mind that wheels will need to be replaced as well.

Dueclaws

+1.
If you want "super" sticky go with the Michelin Pilot Super Sport.
The new M5 BMW has these. I imagine they wear relatively fast, but the PSS received good reviews in the latest Road & Track comparison of the new M5 vs. CTS-V.

ronsc1985

I find all this complaining about the stock tires amusing. MB did not design the E550 to be a race car. The tires on the car are there to provide a good ride and reasonable mileage. The traction control does a really good job of taking care of the wheel spin in straight line acceleration.

If you are looking for straight line traction going to larger wheels is barking up the wrong tree. Narrow stiff sidewalls don't give better traction in a straight line. Their purpose is to keep sidewall roll to a minimum in cornering with the sacrifice of some ride quality.

If you don't believe this take a look at the tire sizes made for purpose built drag race cars. You won't find a wheel size any larger then 16 inches and most are 15. They also have very flexible sidewalls to allow them to flex and make a larger footprint when the weight transfer to the rear of the car during acceleration loads the rear tires heavily. They are terrible for cornering and is one reason you see purpose built drag cars have such a hard time steering when they get crooked; the tires roll over onto the sidewalls.

Large wheels with narrow sidewall tires may look better and corner better but they add nothing to straight line acceleration and the stiff sidewalls are in fact a hindrance.

Dueclaws

The tire size issue isn't limited to the E Coupe, the C63 comes with 255 rears too... and it is a performance vehicle.

threeMBs

ronsc1985, where in my post did I say that one must switch to a larger diameter wheels? One must switch to wider than stock (8.5") wheels (regardless of diameter), since 275 series tires (275/35-18 in this case) do not fit on 8.5" wide wheesl (minimum 9", ideally 9.5"). BTW, this will also increase (not decrease) sidewall height, hence greatly increase traction.

mambrose23

This really is an interesting topic, and obviously there are members here who know their stuff. I speak only from my own personal experience. The 255 primacy tire that came on both my 2011 and 2012 E550 Cabs are a really nice tire, and I understand why MB chose them in this application. I put them on my Mom's C350 Coupe in 255/18 as well. They offer a quiet and comfortable ride and get good milage. The car really is a nice driver with them. I changed to the 275/30/19 PS2 because I wanted a more spirited drive from my car. It's still nice, but certainly a bit noisier and slightly harsher riding. But that's what I was willing to trade off. Regarding acceleration, and having both set ups in both 550 Cabs, I can say that the width difference and tire compound does make for a bit less wheelspin. Incidentally, we have a similar size set up on a 2009 M3 in the family with the newer Pilot Super Sports replacing the worn PS2's on it. The SS is a far superior tire from what we noticed so far, and will be on my car when mine are done. And yes, the new 550 is more than a match for the 413 hp less tourquy M3, at least in a straight line. Lastly, regarding the traction control, MB's system has gotten better with each generation. I remember thinking both my 500 and 550 CLK's were quite dangerous in the way that the system cut engine power at the slightest hint of wheelspin, often even before I could detect it. The power took seemingly forever to come back on, leaving you hanging sometimes in a bad spot. The newer system doesn't seem as interrupive. Seems they are getting it right just as I'm getting too old and responsible to take advantage of it. lol

np888

Can I just switch out the rears for 265 Super Sports?

ronsc1985

Sorry I took your comment about changing wheels as advocating a larger wheel since that is mostly what people seem to talk about.

Doing what you suggest also results in a 2.2% equivalent higher rear end gear ratio which may also quiet down the wheel spin some if that is a problem you are having.

I haven't experienced excessive straight line wheel spin ever with the stock tires. Last December when I first took delivery I tried on really cold days to induce straight line wheel spin and the traction control seemed to keep it in check nicely. I was doing this since my previous car, a C6 Z06, lit the tires hard in first, second or third on such cold days. The only thing the GM traction control did was keep you from hitting the rev limiter (usually). The MB system is far superior. Maybe they perfected it in F1 before it was outlawed.

What the traction control doesn't so so well is limit wheel spin when accelerating hard out corner in the lower gears. It's not bad but definitely a lot worse then straight line, but of course the lateral weight transfer make the job a lot more difficult.

nizzle

The only problem with that is the "traction control" uses the brakes to control wheel spin which, in turn, slows the car down. If you can find a way to get traction without using the brakes to control wheel spin, you'll be faster

ronsc1985

That's true but unfortunately most anything you do to increase traction has some other detrimental effect for a street car.

I think MB did a good job at evaluating the tradeoffs to provide a really excellent street car that has decent acceleration, handling, ride quality interior room and fuel efficiency.

The only thing I wish is it had a little wider trunk. Someone should tell the Germans that modern drivers are 45 inches and longer. In order to fit my golf clubs in the trunk I have to put them in at an angle or take the driver out of the golf bag.

nizzle

^LOL @ the golf clubs part. Your point about detrimental effects are some what valid. However, a slightly wider & stickier tire wouldn't be that detrimental. Also, I dont see how the addition of a good lsd set up would be detrimental at all.

Dueclaws

I agree, but there aren't any LSDs for a '12 or newer E550C: at this time.

nizzle

ahhhhh I see

ronsc1985

Sticker means softer compound which means greater wear. Even LSD's are not a free lunch. The clutch pack, cone or whatever they are using weighs more and contributes to rotational inertia. That is primarily why, with the easy electronic traction control available today very few cars even offer an LSD.

Not to say an LSD wouldn't be a net gain but there are also downsides. In particular LSD with clutch packs need to be warmed up to be effective since the clutch packs are set up loose at ambient temperature to account for thermal expansion so that the clutch packs can slip at all when warm. When cold they are pretty much like an open differential.

I found this out years ago when drag racing a LSD car. First run of the day it would go crooked then it would be O.K. unless there was a long delay between rounds or the weather was on the cold side. One night in the fall I almost took out the tree and the starter when the car made a left turn during a 6K rpm launch. This was in a final and cost me a grand. I bought a spool the next day.

All this is not a problem with a street car since you have usually run it for a time before attempting to hard launch it. The above is primarily why people drag racing bad mouth LSD's and prefer either spools or locker rear ends.

Dueclaws

A Torsen style like Quaife is a good LSD, they're heavier but don't create a problem with ESP & are durable. That's why we "tried" to install one.....

nizzle

Do tell

threeMBs

I concur. Straight line wheel spin can be controled even with stock tires, but IMHO a bit less so in more powerfull 2012 E550. However, when accelerating hard out of the corner (even in my relatively "underpowered" 2010 E550) back wanted to come around every time on stocks. I removed stocks soon after delivery and am happy with results - 275/30-19 and 265/30-20(intentionally used higher diameter to "control" wheel spin, which it does).

mambrose23

Funny about the clubs Ron. Just got back from golfing myself. Always a pain with the driver. If the trunk was just an inch or two wider it would fit. Not a big deal though.