Streamliner

bob55

All of the 18-Inch Alloy wheels that are made by MB or approved by MB for use on the 231 SL Class are shown in the link below!

Note: Brabus is a European Tuner Company for MB which is why MB has previously approved Brabus wheels for use on the 231.

The site link below shows all the 'approved by MB' wheel options for the 231. Note that you can select from different sizes, (17", 18", 19" or 20") that are available from Mercedes, AMG, and the MB (Eurpoean Tuner) Brabus. All are approved by Mercedes-Benz for use on the 231.

http://www.alloywheelsdirect.net/mer.../all/price_asc

Streamliner

bob55

You're welcome Streamliner and congratulations on your new 231. You may also be intrerested to know that you can use the regular MB Center Caps on Brabus Wheels in place of the Brabus logo center caps if you happen to choose one of the Brabus 18-inch wheel options!

Since you previously mentioned that you like bright silver wheels, take a look at the Brabus Monoblock IV and Mononblock S wheels. Those are polished silver wheels that will really stand out!

As for the genuine 18-inch MB silver wheels, note that the 18" MB 15-spoke wheel option looks 'very similar', (when you see it on the car), to the 19" Multi-spoke AMG wheel that is offered as an option for the 2019 SL 450 when you visit the 'Build Your Own' section of the Mercedes-Benz Website.

A link to the 'Build Your Own SL 450' portion of the MBUSA website is shown below. Click the link and note the standard and optional wheel selection there for comparison with ALL available MB approved wheel options that are shown on the Alloy Wheels Direct Website link that I previously provided in the earlier post. There is also a 'Build Your Own SL 550' which is the 2nd link shown below. Note that the SL550 has diifferent wheel options than the SL 450 does.

https://www.mbusa.com/en/vehicles/bu...oadster/sl450r

https://www.mbusa.com/en/vehicles/bu...oadster/sl550r

D49

That's actually quite an interesting question. Obviously, as you're aware, the only TUV registered AMG forged wheels for the R231 are 19/20". The R230 was sold with 19" forged wheels only.

The following is provided as information only, and I do not guarantee its completeness nor its accuracy. I accept no liability for my providing this information. Before placing any purchase order, consult with a qualified professional.

I took a look through some of the earlier TUV certificates out of curiousity to see what, if any, forged wheels are out there. The SLK models were sold with 18" at their top end, which served as a starting point. AMG does not make forged wheels in house, to the best of my knowledge, and uses Otto Fuchs to make the forged wheels for them. While A1724013002/A1724013102 from the R172 SLK looks like the R231 SL Fuchs design, it is not a forged wheel. Fuchs made the 15" forged for the R170 SLK and the 16" forged for the R171 SLK also.

The wheel you want is probably the 18" forged Fuchs made wheel for the R171 SLK and others, and was sold by M-B AMG under the name "Alresha". These are confirmed as forged by the Mercedes-Benz leichtmetallrader directory and by Otto Fuchs KG. This came in two specific types, and are surprisingly cheap for forged wheels.

8Jx18 ET30 245/40 & 9Jx18 ET39 265/35 A2114013702/A2114013802 or B66474244/B66474245 from a W211 E
7.5JX18 ET37 225/40 & 8.5Jx18 ET30 255/35 A2094012602/A2094012702 or B66474242&B66474243 from the R171 SL (and a lot of other models)

Ideally, you would want the wider wheel for the possibly greater tyre contact, but you would need to check using a wheel offset comparison tool online and your own car extensively to confirm that this would fit cleanly with your car. This I leave as an exercise to you.

There may be another set of wheels that would be appropriate: the multi-piece AMG Style IV set. I however cannot find a single Mercedes document explicitly stating that these are forged wheels through. They are certainly priced much higher though, comparable to current forged wheel options.

https://www.fuchsfelge.com/en/wheel-...wheel-357.html

http://www.alloywheelsdirect.net/mer...esha_wheel_599

http://www.alloywheelsdirect.net/mer...esha_wheel_680

edit: corrected typo "The R231 was sold with 19"" to "The R230"

Streamliner

bob55

FYI, the original versions of the SL 550, (2013 was the first year of the 231), came stock with 18-inch MB Twin Spoke wheels and there are (2) other 18" wheel options available for the 231.

However, 19-inch MB designs and 19" AMG wheels were available as 'extra cost wheel options' during the pre-facelift period 231 production. .

Also, I would advise against using any of the SLK wheels on a 231 SL Class vehicle. There is a huge difference in weight between the SLK and the SL Class.

D49

I know. My information was about forged wheels only. There is sadly a lot of confusion even from M-B about their forged wheels. If you saw my thread about B07 Carbon Ceramic Brakes, you will know that even M-B's internal information about their own forged wheels on EPC & ODUS can be incorrect!

Addendum: Those slightly narrower SLK wheels are also viable for the CLC and CLK of that era. The CLK is pretty much the same weight as a current SL, and the wheel design is obviously not an "ultra-light" racing wheel pattern. The other slightly wider was for all E class models which can be much heavier cars. I sincerely doubt weight would be an issue. The main question would be about offset and clearance, especially with brake calipers. I understand from the original poster's other thread that he prefers the 450 because of the ride compared to the larger engined models. I would encourage the original author to read my thread about the different M-B braking systems, which not only improve handling, braking performance and safety.

Dr. Manhattan

I completely get where you're coming from with this. I've never understood the widespread acceptance of the current "wagon wheel" craze that has infested the entire industry. The only way I'd put 18s on an SL would be if 17s wouldn't fit, or you couldn't get the right tires for them. We all know why larger wheels don't work as well, yet so many people continue to buy them. Over at Porsche, they've elevated it to a marketing art form. They equip their sports models with ridiculously large wheels...and then make even more money by selling wheel-and-tire insurance! If the wheels were the right size, they wouldn't need insurance!

To your question regarding 18" MB wheels...in 2018, the 450 configurator listed, in addition to the optional wheel you pictured here, an accessory 18" winter tire/wheel package. The wheels offered were listed as "AMG' wheels, and were the exact same width and offset as the 450's standard 19" wheels. These AMG 18s were cosmetically identical in design to the base/standard 10-spoke wheels shown on the 2019 configurator for the SL63. I really liked those wheels, and when I was on the configurator last year I couldn't understand why they didn't offer them as another one of the regular option choices, like the ones you have pictured here. Of course, your taste in wheel design is probably different than mine, but I just thought you should know that they sold an 18" AMG wheel for you as recently as last year.

bob55

Update: In addition to the Post #2 LINK to Alloy Wheels Direct that shows ALL wheels, (and sizes), that are specifically 'approved by MB' for use on the 231, I have also just added several LINKS to the "Build Your Own' SL 450 and SL 550 to Post #3 above.

Note that in the 'Build Your Own' sections of the MBUSA website, the wheel options are no longer the same for the SL450 and SL550 models..

Streamliner

Streamliner

D49

Those are the Fuchs made forged 19/20" wheels for the R231 SL65. They were optional on the R231 SL63, and available on some rare SL500 / SL550 such as the "Mille Miglia 417" edition or the "Designo" edition (for some countries for some select years), usually with accompanying datacard VeDoc code #PEC. As a warning, a set of those wheels is extremely expensive. The R231 AMG SL and R231 SL have slightly different wheel offset pairings, but the R231 AMG SL wheels fit without clearance issue or spacers on the R231 SL. The reverse is not necessarily true with regards to the brake callipers, especially for R231 AMG SL with the B07 brake package. If you're interested in the rotating weight difference between AMG cast wheels and AMG forged wheels, see my other thread where I provide weights.

In Germany, any wheel installed on a car must be prepared with a certificate from the TUV to certify compliance. This TUV certificate lists all the M-B made wheel options applicable to the R231. Please note that for that particular forged wheel, the colour codes as listed on the certificate actually incorrect! If you have access to Daimler's ODUS system, or visit your local dealership to do so, you can see good pictures of the wheels. Alternatively, alloywheelsdirect do have photos of the wheels. M-B is aware that their certificate is wrong.

R231 SL: <here> see page 6
R231 AMG SL: <here> includes pictures

Streamliner

D49

Streamliner, thank you for your kind words. I am a R231 owner who has extensive experience with the car and its parts, as well as Daimler's systems.

As a general note, there are 3 groups of wheels. M-B wheels for the R231 SL, AMG wheels for the R231 SL, and AMG wheels for the R231 AMG SL. Most M-B wheels are made in-house, but M-B & AMG have used other companies including Fuchs, OZ and Borbet (the legendary SLR turbine wheels). The R231 wheel options on offer have changed wildly from year to year and country to country, especially as the old option #950/951 AMG Sport Package became offered as standard on the R231 SL, and then the R231 SL became listed as "AMG Line".

To answer the question posed by Dr. Manhattan above, there is actually some logic as to why this trend for larger wheels has erupted. Perhaps sadly, in the vast majority of countries, no special driving license is required to own fast cars. The rate at which modern engines have developed is incredible, allowing for better emissions performance, fuel efficiency and simultaneously horsepower and torque! Cars with engines well over 500hp can be found not just in the realms of exotica, but in family sedans, SUVs and of course our R231 SLs. The result is that it is perfectly easy for a less than competent driver to get themselves into quite serious trouble. As such, there has been a lot of development in braking systems and larger disc rotors, not just for emergency braking but for sustained braking performance and even for electronic stability including traction control where brakes are applied to individual wheels to maintain traction. Front brake disc rotors of sizes 400-410mm (15.7-16.1") are now common on M-B AMG and BMW M cars, and I believe Lamborghini released a SUV with a giant 440mm (17.3") front rotor. The R231 SL's B07 package has a front rotor so large that only certain 19" front wheels can actually clear over the brake calipers. If there is any significant taper to the internal barrel of the wheel, it will not fit. There is simply no way that old 15"/16" wheels will clear modern high performance braking systems. It is true that 18" and smaller wheels will give a slightly more cushioned ride, but there are tradeoffs. The increased tyre sidewall flex under cornering would make handing mushier, and extra tyre rubber is extra weight that has to be spun up every time the car moves. Had M-B designed the car for increased sidewall profile on 19" or 19/20" wheels, the front knuckles and rear axles would have sat higher, raising the centre of gravity and make handling poorer as the R231 SL is not particularly light itself. A SL is no way a true sports car, but it is a "sporty" tourer with luxury features and some balance between comfort, handling and performance needs to be struck. Where that line is drawn is an individual choice, and there may be several wheel options that fit depending on your brake package.

Wolfman

Just as I was looking a the pics again, I realize just how classy and timeless this wheel design is
I purchased these wheels in 2013 for our first R231 SL. Those were SL65 standard wheels (polished face/titanium color) which were an optional wheel upgrade for the SL63 at the time. For the facelift SL65, MB simply used a fully polished version of that same wheel. I believe the wheels for the SL63 are now a bit more satin finish (looking at D49's wheels) and then there is a smattering of other color combos as was described. Same wheel either way.

All will work on the SL450 and SL550 as a bolt-on. I have used H&R spacers in addition as I like a wider stance. Makes the car look more planted. To D49 who I assume is in Germany; I likeTUV certificates as they provide certainty that a product will perform for its intended purpose, but in the US nobody cares. Anyone can pretty much do what they want...

Long story short, I still love these wheels on any R231 SL. My favorite is the fully polished version.

D49

These particular 19/20" wheels actually come in 6 different colour combinations. These were:

"Polished with clear varnish"
"High sheen finish with himalaya grey internals"
"High sheen finish with matte black internals"
"High sheen rim flange with himalaya grey spokes"
"High sheen rim flange with matte black spokes"
"Red rim flange with matte black internals"

There is actually 7th listed on EPC (ES2 code 7X23 "High gloss polished w/ black"), however this corresponds to option code RXA, which does not apply to any R231 SL for any region that I know about. No stock of it exists in the Stuttgart GLC either, and I do not believe it has ever existed. The standard R231 AMG SL65 wheels were the first on the list with ES2 code 7X15 "Polished with clear varnish". These were not offered with the R231 AMG SL63 as an option, with next 4 listed being the options depending on market. The final colour with the red outer rim belongs to the R231 SL500/SL550 "Mille Miglia 417" edition.

I personally opted for the high sheen finish with matte black internals, as shown below. I prefer darker wheel interiors as dirt from the roads is less immediately visible. The original wheels that came with my car were the same 5-spoke wheels that Streamliner shows in his "2019 SL450, just couldn’t wait!" thread. While they looked nice enough in the pictures, in person they left me rather cold. To me, they felt rather generic with little relation to the rest of the car's design. In my opinion, the car's aesthetic is to be a bit special without being excessively showy or vulgar. Personal tastes will obviously differ, but I love the look of my wheels.

Dr. Manhattan

Yes, those are the 19" versions of the 18" AMGs that I'm referring to. Why they only offered the 18s in a winter wheel/tire package is beyond me, but they do exist, nevertheless...and again, they have the same width and offset as your stock 19s. JMO, but I think they'd look brilliant on your car.



I understand the need to clear modern brake packages, but even the SL450 has wheels that are 1" larger than necessary to clear the standard brakes. Why? Pure cosmetics. If the car came with 18s, anyone ordering the optional brakes would simply be forced to up-size their wheels. It could even be part of the package. 911s are even worse...a 911 S comes with 20s (!) when 18s will clear the standard brakes quite nicely. Why? Again, pure cosmetics. While a 911's CC brake and rear-steer options require 20s for clearance, there's no good reason to force everyone else to put up with the added expense/headaches of 20" wheels/tires. It's odd too, as it's not like Porsche to miss out an opportunity to charge extra for 20" wheels/tires.

Increased sidewall flex will negatively impact only initial steering input feel...that is, when you first twitch the steering wheel, a slight added delay in the response of the car will be noticeable. Once the car settles into steady-state lateral loading, no difference will be noticeable (and likely not even measurable). In any case, the difference we're discussing is probably not going to matter to anyone with a non-AMG SL.

While it's true that, tire diameters being equal, reducing a tire's wheel size by 1" will typically add about a pound of weight in rubber, you've failed to take into account the accompanying much greater reduction in wheel weight when reducing wheel size by 1". Metal (even aluminum) is far heavier than rubber, and reducing a wheel's diameter removes all of that additional greater weight at the rim and outer spokes...a best-case scenario for decreasing the dreaded flywheel effect that you referred to. While a larger brake rotor may be able to handily decelerate itself and the necessarily-larger/heavier wheel, as you yourself pointed out...all that increased rotating mass (also un-sprung weight that will harm rough road handling and ride quality) will need to be "spun up every time the car moves". On a car like the 450, which has enough traction to achieve maximum acceleration without much tire spin, larger/heavier wheels will noticeably slow the car's acceleration. And, if the wheels are larger than necessary to clear the standard brakes, they will also increase stopping distances. The wheels on F1 cars don't need to clear their inboard-mounted brakes, so their designers have shrunk the wheels to 13" in diameter (in spite of the resulting large increase in tire sidewall height) in order to minimize the cars' flywheel/un-sprung weight effects. While larger-than-necessary wheels absolutely look better to many folks, each of us has to decide whether the performance/cost penalty of that choice is worth it or not. To each his own, as they say.

TennesseeZ4

Just a note on the F1 reference: actually brake tech there is outboard at this time (see attached photo), and just watch the carbon fiber brakes super-heat and glow red when really pushed to the limit. On the wheel size, the rationale for retaining the 13" rim for so many years has been the desire to minimize the cost associated with the structural changes that would create to accommodate newer suspension geometry. Now, with the 2021 rules changes being hashed out, the move to an 18" wheel is quite likely as it fits within the overall envelope changes. 13" has been the standard for years, but the sporting regs will be changing to better align with current road wheel aspect ratios, according to FIA race director Charlie Whiting.

Wolfman

Streamliner

Dr. Manhattan

Both BMW and Cadillac use 18s on the smaller M cars and ATS-V, respectively, though the cosmetic 19s are optional on the BMWs. Throughout the '80s BMW also stuck with round headlights when the rest of the industry went on a square light binge. They tended to stick with what works best, rather than give in to fads.

Wolfman

BMW tends to stick with what works best? I think you are looking hard to find something that fits your argument. They have been the worst offender forcing crappy run flats on customers which neither worked well and were universally hated. And while you can get some 18" wheels on the base M3/M4, nobody buys these. Virtually all are sold with 19" or 20" wheels. Even the tiny M2 is offered only in 19".

D49

I believe you are somewhat overestimating the amount of weight added by having 1" extra of aluminium spoke and 1.2" of barrel circumference. I do not have my numbers to hand any more, and obviously not strictly comparable but from memory the AMG forged 20" rear is 10-15% lighter than the AMG cast 19".

Dr. Manhattan

You can tell just by looking at those multi-spoke AMG cast 19s that they're probably quite heavy. However, the suggested AMG 18s, whether cast or forged, are probably a different story.


Performance benefits of a smaller wheel:

Acceleration/Deceleration – Is significantly improved due to the reduced rotational moment of inertia (flywheel effect). A 2 lb saving on each rim (8 lb per car) will have the same effect on acceleration/deceleration as lightening the whole car by 40-80 lbs! The rule of thumb is that each 1 lb saved at the rim equates to 5-10 lbs of static (car) weight. Remember – the moment of inertia is equal to a cylinder's mass times the square of its radius, and that assumes a solid, featureless "wheel" with equal thickness throughout...that is, (in the case of a front wheel) an 8" x 19" solid billet! We all know that actual road wheels have more of their mass contained out in the rim than they do elsewhere. So mathematically, even a small increase in rim diameter will result in a very noticeable gain in flywheel effect, because almost all of the additional mass will be located in (mathematically) the worst possible location...way out in the rim (barrel). Regarding the resulting effect on acceleration/deceleration, the negative effects of that flywheel gain could very easily exceed any benefit of your claimed overall weight reduction due to forged 20s vs the suggested 18s.

Steering – More precise steering input & better turn-in response due to that lower flywheel effect. If you've ever held the ends of the axle of a spinning bicycle wheel in your hands, and then tried to change the orientation of that axle, you'll know what we're talking about here. And, if you've ever tried the same experiment with two different wheels of equal weight, one a 26" with an alloy rim and the other a 20" with a steel rim...well, we wouldn't be having this conversation, because you'd already know how much easier it was to change the axle orientation on that 20" wheel.

Road Holding, Handling, and Ride Quality – Any reduction in un-sprung weight means the spring/damper combination will work more effectively (have less work to do) while trying to keep the tires in contact with the road. Whichever wheel, 20" forged, or 18" cast (forged?), is overall lighter will have some advantage/benefit in this area.