Today, I completed my wheel & tire changeout. I took off the original-equipment staggered 20" AMG wheels and Pirelli run-flats and replaced them with four, 19 x 8.5" W221 AMG wheels with Pirelli Cinturato P7 AS Plus tires. Since the pros and cons of staggered wheels have been discussed here many times, this post will simply document the process I followed and mention a few details I learned along the way.

My main objective was a more luxurious ride and after one day, the difference is immediately noticeable and just what I hoped for. Bumps and expansion joints the car used to bang over now go by with just a soft thump and the car is noticeably quieter on all road surfaces. It's going to be a real pleasure when we get out on a road trip.

I had the Cinturato P7 tires on my previous car and am noticing them more and more on BMW and Audi cars, so I know they are excellent tires. They score very highly on Tire Rack's scale for noise and ride comfort and have a higher score for steering response than Bridgestone Quiettracks that some here are fond of. Since these high-rated comfort-oriented tires are not available in size 275/35-20, I felt there wasn't a good option to get more comfort and quiet with the 19 or 20" staggered rear wheels, at least not using Tire Rack ratings. This was my primary reason to go square, to get the tires I wanted. But there are two other benefits as well: first, I can rotate the tires to get more life out of them and second, if I had a rear tire blow up on the highway somewhere, I'd have many more options to get a replacement 245/45-19 tire to continue the trip. I fear that 275/35-20 tires could be hard to find in out of the way places.

So, the issues I ran into doing the changeover:

1. The particular 19s I chose had a 43 ET vs. 38 on the OEM wheels. There are 19s with 38 ET, but I liked the style of the wheels I chose and decided the 5 mm difference wouldn't be particularly noticeable
2. In back, I compensated for the 1" narrower wheels by adding 15 mm spacers. With these I had to track down longer wheel bolts with 60 mm shanks. These are not available (that I could find) with the factory "flower" caps, so for the moment, I have different bolt types front and rear. I will probably buy aftermarket 45 mm bolts for the front someday, but am in no hurry as I have both wrenches
3. The tire load index spec is a little odd. On the 18 inch factory wheels, it's 100 all around but on the staggered wheels it's 99 in front and 102 in back. Since I'm not planning to take the defensive line with 600 lbs of luggage to the airport, I don't think there's any harm in having the same load index for all four wheels
4. And finally, the staggered rear 20s with tires are freakin heavy! I think I cut unsprung weight by about 20 lbs on each side of the car!

Hope some of this is helpful to anyone else pondering the staggered wheels and RFT tires!

 

Thanks for your comments. I've been contemplated the same switch (going from staggered 20s with RFT to square 19s with non-RFT). Was your decision to use spacers in the rear cosmetic only?

 

Yes, I consider the rear spacers cosmetic. The car would have looked odd without them, IMO

 

Those are great tires, thats what I used to run on my LS460s.

 

Some issues I see:

1. The Cintaurato P7 AS+ are not XL tires and are not built to carry the weight of the S-class. You should have gone with the regular Cinturato P7 AS's which are XL rated if you had to have Pirellis. Any reputable tire shop would have refused to install that particular tire on your car since it isn't the correct rating.
2. Your NVH ride improvement had everything to do with ditching the crappy hard riding RFT's and going with standard tires, not downgrading to 19" wheels which are narrower in the back. You would have noticed the same ride quality improvement if you kept your significantly better looking stock 20's and went with these tires. You could have paid the same or slightly less than what you paid for the Pirelli's on smaller wheels and kept the beautiful stock staggered wheels. They are also a big name brand and are readily available. My ride improved tenfold as soon as I made that switch.
3. IMHO, those narrow, smaller tires don't look right on a car with the more aggressive looking AMG body package, especially in a warmer climate like Austin where you never need to worry about switching out to dedicated winter wheels/tires.
4. Those chrome wheels are going to be harder to keep looking clean, especially with the way our cars shed brake dust. At least the gunmetal colored stock 20's did a decent job hiding the brake dust.

What did you end up doing with your 20" wheels?

 

Dave, interesting points, thank you. I would love to have been able to try your car and see how good those General G-Max tires are on 20" wheels. I did look at their Tire Rack ratings and they're probably great tires, but they aren't in the top tier in ride and noise comfort, at least in Tire Rack's system.

The load index business is a bit of a puzzle to me. A 99 rating says each tire can support 1,709 lbs, a 102 is 1,874. My reasoning is if Mercedes allows something between a 99 and 102 for a 4,600 lb S550, there must be a fair margin of safety in that range. Does a wider/taller wheel/tire require more load capacity? I'm sure I have more to learn about these ratings, but it seems four 99-rated tires would support ~ 6,800 lbs and that is well beyond the GWR on the fuel filler door (6,019) and any weight I ever expect to carry.

EDIT: Dave also brought up the "XL" or load rating of the tires, and this is also a bit difficult to interpret. XL-rated tires are reinforced to operate with higher air pressures (up to 41 psi) and are also specified for "high-performance" vehicles. When I researched this in my owner's manual, I found that a RWD S550 with summer tires can have different load ratings, just like it has different load index values:

1. 18" wheels and tires are spec'd for "Standard Load" or "SL"
2. 19" front wheels are "XL" and 19" rears are spec'd for "SL"
3. 20" wheels are "XL" front and rear

Since I plan to run my tires somewhere in the 32 - 35 PSI range, I don't feel concerned about using SL tires.

I was a bit surprised after taking off the 20s to find that the tires actually have more tread than I thought. Three measure at 9/32s and one at 8/32s. Not sure what I will do with them; the obvious answer is to sell them as a easy bolt-on upgrade to someone locally. But if I can find room, I might keep them for the day when I sell this car so I can put it back to the original config for the next owner.

 

Tom, if you plan on holding on to the tires, you should give them a good cleaning then apply a good dressing to the "entire tire" like 303. If not driven on for 4 to 5 years, the tire will dry rot fairly fast. Check date code on your tires, then add to them how long you may hold on to them. It may be worth it to sell them if you plan on holding them for several years.

What did you pay for the Rims and are they OEM or Replicas.

Ride looks nice!

 

Keep in mind the weight distribution and that the individual tire load will increase during braking and cornering. Point being you don't have as much margin as your calculation above would suggest.

 

The wheels are Mercedes OEM, made in Germany. Two were newly-chromed and beautiful; the other two were dirty but cleaned up pretty well. I paid $475 ea for the nice ones, and $425 ea for the dirty ones for a total of $1,800.

Happily they all balanced perfectly and ride like a dream. I was a little anxious one or more might be bent or have some flaw, but all four seem to be good wheels.

 

I had a long talk with the guys at TireRack about this, the consensus is thats not true and it doesnt matter as long as the load rating is sufficient for the car, which it is on those tires.

Also not true. For sure better tires on the 20s will help a lot, but they will not ride as soft as great tires on 19s which will not ride as soft as great tires on 18s. Its just physics.

 

Another pic of the finished result ...



Oh, ok, one more ...

 

The MB engineers say it needs XL tires, so I'd go with their recommendation over what some salesman at an online tire seller has to say. But I'm not saying that Tom will have an issue with those tires as I image he is a pretty tame driver based on his downgrading to 19" wheels that are also narrower in the back.


Thank you for that Mr Science. But you are wrong about the NVH for 20's vs 19's. My 20's are extremely quiet, provide a very comfortable ride, and absorb bumps in the road as well as any S-class wearing 19" rubber of similar quality. The 20's on these cars are not some rubber band tires that you see on many ghetto rigs with 30" wheels. They have lots of sidewall to help absorb the road imperfections that the Airmatic doesn't on its own. The only advantage to 19's or smaller would be that they are better able to protect the wheels if hitting a deep pothole or large debris in the road. The ride quality certainly isn't any better. In fact, they'll likely be worse when it comes to cornering.

 

Don't confuse what the engineer thought the car needed with what load ratings are available in what sizes of RFT that fit the application. I have a long history with TireRack and I would be astonished if they told me that lower load rated tires than OEM were okay. And he was not a salesman, he was one of their tire testers.

Just by going with non runflats you're thumbing your nose at Mercedes engineers so get off your high horse lol

I'm sure your 20s are very quiet and comfortable, but not as quiet and comfortable as the car on good quality non runflat tires and 19" wheels. How many S Classes have you driven on good quality non runflat tires and 19" wheels? Because I have done so on a car with 20s and good quality non runflat tires and mine on 19s rides softer. Its simply a fact that the thicker the sidewall is the more cushioning goes into the ride. Go drive a W222 on 18s, 19s and 20s and see for yourself, they will all be on very similar OEM runflats so it should be a fair comparison. I have done exactly that several times and the difference is there. Its not overwhelming like some people say it is, but its there.

If you drive his car and your car back to back, his will ride softer.

I do agree the only way the square setup improves ride is you have options for better tires. The non staggered setup will reduce noise too since less rubber runs along the road at the rear.

 

I'll take the Pepsi challenge with my General AS-05 tires on my stock 20's vs ANY brand of tires on 19" wheels on any S-class. My car has virtually no tire noise, even at speeds of 80 mph. It's more silent than any Lexus I've owned (I've had 4 LS's, a GS, and an ES). And it also rides smooth as silk. It's almost as if you believe the Airmatic suspension doesn't even exist and all NVH is handled solely by the tires on the car.

My wife's Honda Odyssey has tires that are 235/65R17 all around. So according to your logic, her tires would automatically provide a quieter and softer ride because of the smaller wheels with much more tire sidewall, right? Well that's not even close to being factual. The ride in my car is 1000% better than in her van. In the Odyssey, you feel almost every little crack in the road and it can often be jarring. In my car, you hardly ever notice those cracks are even there as it quietly wafts right over them. You'd have to have a butt as sensitive as Streamliner's to have any chance at noticing a softer ride on 19" wheels.

 

Of course the ride of your Odyssey is not going to be better than the ride of your S Class because it has taller sidewall tires. But your Odyssey wouldn't ride as well as it does if you put the 18" wheel option on it. THATS the point.

I'm not going to continue to argue with you, there's no point. You're just wrong...luckily all the other posters here already know that lol.

 

Apparently you're too young to know what the Pepsi Challenge is are are still missing the point. You said taller tires would ride softer than shorter sidewall tires. Not even close when it comes to my wife's Odyssey which will jar you going over bumps....for the 2nd time.

 

I do know what the Pepsi challenge is, and like I said I have a good friend with a W222 on non runflat high quality 20s I ride in all the time, my car on 19s and good quality non run flats rides softer. I also have driven the W222 all brand new on 18s, 19s and 20s back to back, and the difference in ride softness between all three is clear. Methinks you're the one who needs to try the Pepsi challenge lol

I said nothing of the kind about the Odyssey, I made it very clear. I am comparing different sidewall aspect ratios on the same car. Of course your Odyssey will never ride like an S Class on 20s. But, compare your Odyssey on 17s to an Odyssey on 18s, the one on 18s will ride firmer.

Not sure if you really do get this and are just trolling...or if you're trying to convince yourself of this or what...but to everybody else this makes perfect sense lol

If you're happy with your car on 20s, thats great. It looks great on the 20s. It just rides slightly firmer than it would on 19s or 18s. Which is obvious to everyone but you.

 

I removed a few posts.
Please keep comments on topic. Thank you.

Bob

 

So the 19's fit on the larger brake Sport or AMG s550?

Are General tires made by Continental?

With the smaller rear tire is there any issue with tire spin? I get that depends greatly on driver but on my old s550 with the Renntech stuff even with the staggered it was hard to take off from a dead stop without feathering the pedal.

The being able to rotate the tires is a huge plus.

 

The AMG 19s I used fine fit over the AMG sport package front calipers.

With 8.5" wheels in back and 245mm tires instead of 275s, I'm sure there's less traction than with wider wheels and tires.

Even the valet at Truluck's approves our square set-up, he left our car out front all evening while we dined!

 

The Pepsi challenge? LMFAO!! That was a long time ago haha!! You shouldn't drink soda anyway

 

Continental AG of Germany has owned General Tires since the 1980's. But General Tires are made in the USA.

4matic works wonders when it comes to tire spin. Even with the car tuned to 550 hp and 650 tq, there is virtually no tire spin from a dig....at least not with my staggered setup on stock 20's running the sticky Generals.

Just image if you still had those beautiful 20's on it. They may have shined a spotlight on the car.

 

Last comment on this ... since doing the new wheel/tire combo I've run the car almost exclusively in 'Sport' mode, and absolutely love it this way. Completely acceptable ride comfort - even on junky pavement - and the car just feels smaller, lighter and more agile.

This was the other thing I hoped to accomplish. I may still use 'Comfort' sometimes, but the default is 'Sport' from here on out ...

 

I actually really like sport mode in this car. It almost seems to ride better....

 

Great look. I'm considering the same thing but I don't want to loose the sleek look that I have with the sport body style. Is the profile still the same?