Utopia Texas

I used Michelin Pilot tires on my 2008 SL550. My 2017 SL450 came with run flat tires and my salesman said the suspension for the SL450 is set up to only use run flats. Is this true or BS from the salesman. After these run flat tires are worn out can I change to Michelin Pilot sports and expect the same smooth quiet ride as the run flat tires?

threeMBs

What a nonsense. Never trust a salesman.

ibanezking

its true that the Runflats give a firmer ride than regular tyres due to the very thick sidewall
So yes, the car will have its suspension tuned to what it has from new - which is runflats

My wifes mini had them on it when she bought it and it gave a really harsh and crashy ride - so we put regulars on it and that softened it down a bit

But her new SL400 feels fine with the runflats
In fact it does a GREAT job of soaking up the bumps

Wolfman

Complete BS, as stated already. The suspension is also NOT tuned for run flats.

Run flats are installed for certain markets. Germany uses performance conventional summer tires by default. Run flats are simply a chargeable option.

I have always taken off the run flats right away and put on performance tires (Michelin Pilot Super Sports). Makes for a better driving experience.
In case of a flat I use the Continental Tirefit kit...

ibanezking

Its not BS Wolfy

The suspension has to be tuned to something! Some type of tyre - some brand or whether its regular or runflat. At somepoint in the factory when some team of techs is programming the Comfort/Sports/Sports+ modes.............. they have to drive the car............ on tyres.

Its quite conceivable that the cars have a couple of different programs onboard that can be "set" depending on the country of destination.
In the UK, most car brands now come with runflats as STANDARD - so it makes sense that the vehicle is optimised to work well with those.

Otherwise - you'd get people test driving new cars........ and saying "hey, the ride isnt so great Mr Salesman"

and he can reply........... "oh its OK, you put up with these runflat tyres for the first 15 to 20,000 miles and then you can replace them with regular tyres, and the ride will improve as the car was designed to work better with regular tyres...."

just like the cars probably get optimised/programmed/set to pass the emmisions tests of the country of destination - probably different for each country - in terms of the amount of emmision and at how many revs the test is conducted at.
But maybe thats a sticky subject for you Septics and Audi's optimisation

Wiz

Some manufacturers do claim that certain models are set up for run flats (BMW certainly do) so it's not absolute BS. Having said that, lots of people do find the car rides better without them anyway - and of course they can't be puncture repaired, are loads heavier and loads more expensive, so there is good reason to investigate it with Merc direct. This link might help:


https://www.national.co.uk/information/run-flat-tyres


** Industry Views on Replacing Run Flat Tyres with Conventional Tyres

National Tyres and Autocare

National recommend replacing like with like, i.e. keeping run flat tyres if that is what your vehicle was originally equipped with. This is because the vehicle manufacturer has set the vehicle's suspension to suit run flat tyres, so changing to conventional ones could have an adverse effect on handling.

However, if you do choose to change to conventional tyres, don't forget to purchase a spare wheel and tyre – or failing that, a can of tyre sealant to give a temporary repair./p> Also, if you choose to replace with conventional tyres, then note:

1. make sure you fit the correct tyre size, speed rating and load index
2. don't mix conventional and run flat tyres across the vehicle, i.e. replace all four tyres at the same time
3. get advice from your insurance company to make sure your cover remains valid

BTMA

The BTMA (2005) stated that retro-fitting conventional tyres in place of run flat tyres would:BMW

BMW promote run flat technology because of its advantages for driver comfort and safety. They point out that when run flats are fitted as original equipment, then vehicles' braking and suspension are set up accordingly, so changing to conventional tyres may affect the handling characteristics of your car. However, they do say it is possible to fit conventional tyres.
TyreSafe

Tyresafe recommend that drivers do not change their vehicle set up from run flat to conventional, because of the adverse affects this could have on vehicle handling due to the vehicle set up.

Wolfman

I am glad you are making all these assumptions.

There is no suspension coding happening at a car level during production no matter what tires are installed. In Europe, there are only 2 sets of springs for the SL400 (reg. & sport suspension)

Wolfman

I am not sure why you are posting this. Maybe this is relevant for some UK readers?

These topics have been covered countless times here and on the BMW forums (for a decade plus).
People have been switching out run flats for regular tires forever with improved results.

While BMW did have suspension tuning for their cars in the early days of run flats (due to the early generation run flat tire designs which were significantly stiffer than todays tires. They also featured stronger rims in the old days). This is now a wash.

Wiz

Not sure why you're posting this. Maybe it's relevant for some US readers

Wolfman

It is. For the thread starter

threeMBs

+1

Wiz

Equally it's kind of narcissistic to believe that your contribution to the OP was sooooo much more helpful than mine

Wolfman

Since run flat tires were introduced on MB's, this has been a much discussed topic. So there is a lot of useful information on these forums already.

To your point I like to provide relevant information to the OP, not general or assumptive info. If you have anything specific to counter, please share

The R231 works great with non-runflats. Have been doing so. Michelin Pilot sports versions (I prefer the Super Sports) are about as good as one can buy. I also used Pirelli Sottozero for snows as well. Good choice if driving in winter the considered.

Dealers, at least in the US, will know very little about the tech of the car and will rarely recommend anything that is not factory.

Wiz

Ok, you said it was complete BS, but you're wrong. You offered no evidence whatsoever, only your worldly opinion. I, at least, offered some evidence. I also happen to be connected to the motor trade and know that some cars are specifically set up to work with run-flats, so it isn't BS.



Despite that, I didn't feel the need to quote your comment and make some disparaging remark about it, only you did that, which is a really dick move. But hey, hopefully you're feeling good about yourself and that's all that matters right?

Wolfman

A dick move? Sorry you feel this way.

I am not sure what evidence you are looking for? The lack of MB part numbers for such a thing and needed programming setting in MB's factory coding software (or Star Diagnostic for techs to code that)?

I am providing actual driver input and a little knowledge about Mercedes internal working.

Utopia Texas

I have no idea how many miles I will get from this initial set of run flat tires. The reason I asked the initial question is because all 4 of my recent passengers in the 450 say it rides smoother and quieter than my 2008 SL550 did with ABC and Pilot Sports. I have to agree after the first 1,000 miles so far. The current 450 has the run flats and standard suspension so I am in a quandary over what my next set of tires might be......

Wiz

Ok, I'm providing actual inside knowledge and fact. One of my very best friends does chassis development for BMW and Audi. You may have heard of him, he was the Original Stig on Top Gear, an ex Formula One driver and Le Mans driver. I'm listed in the "thanks" credits in the front of his autobiographical book called "Flat Out and Flat Broke".


We had this conversation in detail when BMW alloy wheels were cracking and leaking air due to the overly hard walls of the run flat tyres. One of our mutual friends had an affected 335i and Perry asked at both Audi and BMW if non-run flats could be used. The answer was yes from both manufacturers, but with the caution that the suspension was set up to work at optimal performance with the heavier, stiffer run flats and running on a lighter more compliant tyre might not give the desired results, especially under on-limit handling. The results of using standard tyres were unknown because they'd never tested them standard tyres.


Clearly, people who never push their car hard or do track days may not even notice. Some people might prefer the softer feel and other might hate it, but the bottom line is you aren't correct to say it's BS because it definitely isn't, some chassis were certainly developed specifically for run flats and quoting other people's posts (ibanezking's and mine) just to dismiss them as rubbish (especially when you're wrong) is frankly a bit of a dick move - or at the least, entirely unnecessary.


The bottom line is that IMHO the OP should do a little more research before sticking on non-oem tyres. Without that, it might be fine, or he might hate them and regret it.

DATURK

I think both sides are right, however there is one other thing here to be considered, Michelin SS will last you about 10000 miles and the run flats well let say I am well over 10k over my SL they still look new, however I'm on my third set of Michelin SS on my S63, food for thought, ooh, on my SL, I think the run flats are doing pretty good as for as the ride comfort...

Wolfman

I think you provided really good and useful information here and it is of benefit for everyone to know about run flats. I also didn't dismiss ibanezking's post whose posts I very much enjoy as rubbish. It's just that neither post pertained to the R231 SL.

Chances are it is relevant info for BMW or Audi and while Mercedes started to use run flats as well, the R231 was not specifically designed for them and these SL's are sold from the factory with conventional tires or run flats coming off the same production line and using the same components. This is clearly not the case with BMW, hence their cautious approval for the use of conventional tires.

People have also been driving these cars for years with conventional tires and it has no impact on warranty, provided the tire size and load rating is observed.

You might not believe it but it exciting to see more fellow SL drivers here and hear about your experience. We can clearly agree to disagree on some things but you have great taste in cars

Wolfman

Short lifespan is synonymous with high-performance rubber. The Super Sports at least seem to last a bit longer than the older PS2's or PS3's.

You are right, we had the Continental run flats on the SL and they felt more compliant than the Pirellis that were on our S-Class...

VegasSL550

I recently purchased a CPO 2013 SL550 with about 12K miles. The dealer installed new Pirelli Pzeros in stock sizes (19" AMG wheels), but I do not believe they are runflats. They do say MO in the side. The car did not have the compressor and sealant in the trunk, although the cutouts were there. I questioned the dealer about this and they immediately sent me replacements to fill the holes.

So here's my question: Does anyone know if this car originally came with runflats and did the dealer replace the original tires with something different?

DATURK

in US comes with run flats.

Wolfman

Thought so too but it appears that some cars with ABC came with conventional tires.

VegasSL550

My car does not have ABC, so perhaps the selling dealer replaced the runflats with a cheaper tire. Doesn't surprise me.....Reno NV MB dealer is one of the worst dealerships I have ever dealt with.