RE: Mercedes tyre 'skipping' - official statement
Discussion
I've experienced this in a few cars too (actually almost every Porsche driven). It doesn't bother me in the slightest, having 4 or 5 clunks when manoeuvring, as I knew what it was and it evidently wasn't causing any harm.
But... have people seen the Youtube videos of these Mercs? It looks way worse than anything I have experienced - constant thumping when pulling out of a drive or junction. Plus, these are not sports cars. More belligerent posters may like to deny that most Boxsters/Caymans/911s are proper sports cars, but those type of cars would have been bought knowing there is at least some compromise - firm suspension, heavier controls, less interior space, performance orientated geometry.
People buying x43s and especially cooking GLCs will not expect this though, and nor in my experience would they get it from other brands. It may not be the end of the world, but Mercedes have messed up here in my opinion.
But... have people seen the Youtube videos of these Mercs? It looks way worse than anything I have experienced - constant thumping when pulling out of a drive or junction. Plus, these are not sports cars. More belligerent posters may like to deny that most Boxsters/Caymans/911s are proper sports cars, but those type of cars would have been bought knowing there is at least some compromise - firm suspension, heavier controls, less interior space, performance orientated geometry.
People buying x43s and especially cooking GLCs will not expect this though, and nor in my experience would they get it from other brands. It may not be the end of the world, but Mercedes have messed up here in my opinion.
kambites said:
Eagle F1s? If so I'm not surprised - they have very soft sidewalls.
I've been fitting Eagle F1 Asym 2's on my ST170 for years now, never felt this.I fitted the latest Eagle F1 Asym 3 earlier this year and now I get a juddering feeling/noise from the front. I first noticed it on the painted surface in a multi storey car park. Didn't hear it all through the year until winter.
No AWD in an ST170 and the Ackerman geometry hasn't changed in the 13-14 years since it left the factory.
I'm wondering if there's been a change in the compounds used by tyre manufacturers recently that's making this more widespread.
I haven't heard of people reporting it before this last year or so, regardless of the weather.
GranCab said:
S'funny how this hasn't been discussed before as it transpires many 2WD cars suffer from it and have done for a few years.
2WD, 4WD, RWD in itself is of no consequence, but there is little doubt that, in some applications, the presence of drive shafts to the steering wheels and the associated CV joints and other hardware is a design consideration that may (or may not) necessitate further compromises.This is a way more complex subject than most people would at first think. Remember also that each wheel has to turn through a differing max lock left-to-right than the other wheel. There will be any number of considerations including, but not limited to, hub carriers, brake calipers, suspension struts, engine ancillary components and wheel arch liners. Retsrictions will often differ from one side of the car to the other, and most likely also between LHD or RHD. Big wheels and huge brakes will exasperate potential areas of concern on the performance variants.
I could go on, but it's pointless, as I didn't design the car. My only point is that there will be very good, and very considered reasons why this happens, and I am absolutely certain that no one here could have designed it any better. This is not a mistake, or a reliability issue.
Edited by Kenny Powers on Friday 27th January 16:45
As mentioned it is due to ackerman not being perfect for scrub but this is not due to manufacturers getting it wrong. To get the best performance the tyres will operate with a level of slip as this is when they deliver maximum grip so on performance cars the manufacturer will often sacrifice tyre wear for steering performance and grip.
It is more obvious when cold as the grip level of summer rubber drops significantly so rather than causing a jacking effect on the axle the tyre slips and you get the judder sensation.
It is more obvious when cold as the grip level of summer rubber drops significantly so rather than causing a jacking effect on the axle the tyre slips and you get the judder sensation.
nickfrog said:
big_rob_sydney said:
It does beg the question though; when other manufacturers of cheap-arsed cars can get it right, why should people spend big money on a "premium" brand, to get it so wrong?
MB can go f
k themselves.
Another beautiful contribution. MB will really miss you as a customer.MB can go f
k themselves.tboxes in my ownership. Sweet FA.big_rob_sydney said:
nickfrog said:
big_rob_sydney said:
It does beg the question though; when other manufacturers of cheap-arsed cars can get it right, why should people spend big money on a "premium" brand, to get it so wrong?
MB can go fk themselves.
Another beautiful contribution. MB will really miss you as a customer.MB can go f
k themselves.tboxes in my ownership. Sweet FA.A comfort issue, yes too right it is a comfort issue. It is bloody uncomfortable.
This is my vehicle;
https://youtu.be/rO5rqpYPNjo
This was the passenger side tyre at 2,700 miles
This is the tyre at 4,008 miles
Driver side tyre is absolutely fine.
Just a comfort issue, year right.
They all do that? Yes right, just seriously think about coming to my home and take my car for a test drive as a potential buyer. Would you buy such an AMG vehicle?
I would walk a mile, but Mercedes say it is just fine...
This is my vehicle;
https://youtu.be/rO5rqpYPNjo
This was the passenger side tyre at 2,700 miles
This is the tyre at 4,008 miles
Driver side tyre is absolutely fine.
Just a comfort issue, year right.
They all do that? Yes right, just seriously think about coming to my home and take my car for a test drive as a potential buyer. Would you buy such an AMG vehicle?
I would walk a mile, but Mercedes say it is just fine...
Kenny Powers said:
My only point is that there will be very good, and very considered reasons why this happens, and I am absolutely certain that no one here could have designed it any better. This is not a mistake, or a reliability issue.
Good reasons? Yes - budget, probably."No one could have designed it any better"? What about all those other mfrs of cars which don't exhibit such behaviour?
I'm quite happy to accept that this is a consequence of incomplete-Ackermann geometry and ultra-low / ultra-stiff sidewalls. But does it REALLY need to be there?
I've seen a number of (rather clever) suspension geometry innovations, from Honda's 'compliance pivot' which removes longitudinal deflection on hitting potholes/other road deformations, mechanical and electrical 4-wheel steer systems to artificially change the effective wheelbase, king-pin-inclination compensators, 'RevoKnuckle'/'PerfoHub' and other torque-steer reducing systems...and probably others I've forgotten about.
So I'm sure those ever-so-clever bods at Mercedes COULD do it better, most probably if they had the budget...which Merc clearly chose to spend elsewhere...
A lot of cars "crab" on full-lock at low speed from Renault to Pork to Lambo. It is annoying at first, but usually harmless, and you get used to it.
The Merc AMG issue sounds a bit worse than normal "crabbing", however. It seems to be up another level of bounce and actually "skipping". More to come here, one suspects.
The Merc AMG issue sounds a bit worse than normal "crabbing", however. It seems to be up another level of bounce and actually "skipping". More to come here, one suspects.
My old GS300 did this, so does the replacement Toyota MarkX. It's definitely a compromise made with the ackerman geometry. It happens on Nissan S chassis too when you fit modified knuckles with reduced ackerman although the stockers don't do it.
For me it's acceptable, you only really notice it when reversing at full lock. That GLC looks shocking though, that's not acceptable for a premium vehicle tbh. Changing tyres isn't a cure it's only masking the issue.
For me it's acceptable, you only really notice it when reversing at full lock. That GLC looks shocking though, that's not acceptable for a premium vehicle tbh. Changing tyres isn't a cure it's only masking the issue.
I had a '99 C43 AMG that did the same. It's down to the castor angle being high, as it is with most high speed vehicles. More castor (ie laying the strut towards the rear of the car, or biasing the top knuckle - on wishbone suspension - towards the rear) helps with high speed stability. But the more the castor, the more the wheels tip over at low speed manoeuvring, which puts the tyre on to its inner or outer shoulder, therefore giving less grip and forcing the tyre to skip.
So Mercedes are right in calling it a comfort issue, because stability at high speed is reassuring.
So Mercedes are right in calling it a comfort issue, because stability at high speed is reassuring.
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