I have done the same with my W213 as AK 19 has. Gone from 20 inch AMG wheels with Goodyear rubber bands to 18 inch with PS4's
The jolting and large thunks while driving up my driveway has gone away.

On a very smooth road the 20's were quiet - however AK and I live in Australia where smooth roads only exist outside politicians houses.

 

I had a slow leak in one of my Goodyear Runflats and a local tire shop fixed it for $20 in about one hour. I don't know the location of the leak. Now all four tires need replacing (30k miles) so I face the same dilemma of whether to stick with the runflats or not.

 

Great review. I just switch from runflats to non runflats on my 20s. I'm not impressed. A little depressed too. The car seems to feel the road more, a little more vibrations that are detectable that weren't before. I bought them back to make sure the tire was balanced but was all passing scores. Maybe I need to go to a smaller rim but my car option for the amg claims to only be 19s recommended. If I went to 18s I dont know if I'd open up another can of worms.

 

Are they the same tire or different?
I use only nonruflats (pilot sport 4s) and they work perfectly. Stickiest tire on the market. There is even an MO version.

 

I switched to regular non-RF. The ride and noise are much reduced after 2k miles. It seems tires need about this to acquire a steady state. I had RF for about 2k before I switched.

Obviously, these companies think you should use RF. They have their reasons, whatever they are. Maybe they are right? But, I'll stick with Non-RF simply because I would like to be able to deal with a bad tire at ANY local shop on-the-spot. And with some luck, right on the road where a flat happens (although that has never been the case yet).

But it's strange about tires these days. The same dealers that sell you car with RF also sell you cars with 18" and 19" wheels, which is another thing I have a problem with, right along side the RF craze. This I'm certain I don't like and frankly do not get. It's bit hard to wrap my mind around the fact they would virtually ruin a luxury's car ride for cosmetics. And don't tell me it's for performance as they put them on SUVs and every car.

So the take-away is I don't trust anyone when it comes to wheels

 

My first experience with run flats was on a 2004 BMW Z-4 roadster. My wife wouldn't ride in it because of the harsh ride. Two BMW 7 series later and the first thing I did was change to non run flats. In my current S Class I immediately replaced the run flats to non run flats. Since 2004 the only leaks I've ever had are with run flats. I carry a small inflator in case of a slow leak. Driving without a spare doesn't bother me in the least even on long road trips. If I had a blowout that couldn't be fixed I'd handle that situation as needed. My wife drives a Cadillac XTS and has never had a tire problem with regular tires.

 

The 20" 35 profile conventional tire's sidewall is almost as thick as the runflats. The lower the sidewall, the stiffer the sidewall has to be.

 

I have RF, Pirelli P7 Cinturato, 18" MOE. When I had a slow leak my local tire dealer was able to fix it on the spot. When I had a "bubble" I had a replacement tire the next day. What situation are you thinking of that your local shop could not fix a RF on the spot, where he could on a non RF?

Of course if you are on the road with a non RF and have a bad leak you must pull over and change your tire, assuming you have a spare in the trunk or wait for road side assistance. With a RF you can also wait for roadside assistance or drive to a tire dealer: two options instead of one.

Here I agree with: To me the most important function of a wheel is the ride quality. The E class is not a "sport car" or a "sport sedan": it is a luxury car. Putting on bigger wheels to me is a classic case of "form over function!"

Several years ago in Consumer Reports they downgraded the RAV4 Limited because the Limited went to 20" wheels vs. the standard 18" wheel. CU stated that their was a noticeable decrease in the quality of the ride. They highly recommended the normal RAV4 but did not recommend the Limited because of the ride.

 

Comparing RF from 2004 to today's RF is like comparing dial up internet to broad band.

Tremendous improvement has been made in the ride quality of RF over the past 10 years. Today's cars suspension are specifically engineered for RF. Manufacturers work with tire manufacturers in the design of RF for their cars.

The marginal ride benefit, if any, between non RF and RF, is negated by the advantages of RF in the event of tire leak. The only real advantage of non RF to RF is the price.

But if you "immediately replaced the run flats to non run flats" as you did on your S Class, while there were still thousands of miles of tread life left on the original RF, then of course there is no savings only an added expense.

 

I agree: Plus that tiny sidewall on the 35 profile tire will not have enough deflection to prevent serious wheel damage when you hit even small potholes, not to mention the large pot holes we have here in the north east.

Even parking and hitting a curb, may cause damage to the those 20" wheels.

 

I have 19” 40 profile and it is no match for the potholes in New England. Had the car for 6 months now and already one tire replaced due to sidewall bubble. The roads here are getting worth each year as government rather spend tax payer’s money on something else rather than roads. I am going back old school on my next car and going with at least 55 profile tires.

 

One year later with my 18" Michelin Pilot sport 4 non run flats, I have to say I have no regrets. In fact reducing my air pressure to fronts 32 psi and rears 36psi has made the car ride even more beautifully. The sidewall flex gloriously soaks up all the potholes and road imperfections/undulations so well. Sure the tires may wear faster, but its worth it! Sidewalls 45 or greater are the way to go against bad roads.

That being said, if you can see potholes, best to avoid them. 2 Months ago there was a stranded W163 ML with 255/65r16 wheels on our country roads with cracked front rim due to a nasty deep pothole in southern Victoria. Glad I got the warning in Waze ahead of time to slow down and avoid the hole.

Since you're in New England and have to deal with winter affected roads, I'd think you cant go wrong with Michelin Primacy Tour A/S for the best elasticity on tires. Also do note Michelin is going to release Primacy 4+ in 2022 rumoured to promise longer tread life with the same comfort levels.

 

I cannot use summer tires unless I get winter tires and I do not drive enough in the Winter to justify that. The lack of a spare tire is also a concern with conventional tires. We have a SUV we use in for long Winter trips which happens to have Michelin Primary tires. We like the Primacy tires, I like it better than the Pirelli runflats on my E300. My last Mercedes had conventional tires and 45 profile, I had it at 32 psi in the front and 36 in rear, 32 psi in front is simply not enough pressure to protect the tire and the rim. I got a few tire bubbles and 1 bent rim running the low pressure. I run 36 psi all around now, usually, higher psi in rear is for heavy load conditions.