A few weeks ago I finally decided that I'd had it with the Michelin RFTs that came on my 2018 E400 Coupe (IIRC they were PS2 ZPs) — they were noisy and rode like the rock wheels on Fred Flintstone's prehistoric vehicle, especially on rough roads (i.e., most California highways and streets these days), and they didn't have much road feel. So although the RFTs had only 8,000 miles on them, on April 12 I laid out $1,417.18 (installed, with tax and alignment included) for a new set of Michelin Pilot Sport 4S tires, which Tire Rack describes as "Max Performance Summer" tires and rates very highly (see below).

I knew I was taking a risk as the car has no spare, but I figured (1) I'm older than dirt and not about to change my own tire under any circumstances, and (2) I have AAA and roadside assistance coverage on my auto insurance and my AmEx, Visa, and M/C credit cards. Besides, I've had only a couple of flats in 50+ plus years of driving except for three about 10 years ago, all on a set of Continentals that seemed prone to picking up nails and screws (dumped those for Michelins — no problems after that). So I figured that rolling the dice was a good bet.

But as Bobby Burns so aptly put it,


On April 23 I had business at a community college in Santa Clarita, about 45 miles from my home in Hermosa Beach, CA. When I returned to my car and began to drive out of the lot, the dash lit up in red letters, "Check Tire Pressure." I did and the sensor indicated that the right-rear tire was down to 16 pounds. My first thought was that the TPMS for that wheel had gone crazy as the was no obvious problem with the tire, so I drove to a gas station about a mile away and checked the tire with my gauge, which showed that it was indeed very low. I pumped up the tire to about its normal PSI of 35, which I verified with both my tire gauge and the TPMS. I felt all around the tire but found no problems, so I kicked into full paranoid mode and thought maybe one of the students had messed with my tire. I decided to drive slowly to the tire shop near my home from which I had purchased the new tires (which had a little less than 400 miles on them at that point).

It soon became apparent that the TPMS wasn't the problem as the warning again popped up on the dash. I checked the pressure again and the computer showed that it was down to 20 PSI. I pulled off the freeway at the first opportunity, found another gas station, and again filled the tire. After that I kept the tire pressure displayed on the dash, watching it slowly dissipate as I drove. I had to make two more stops for air, the last one only 1½ miles from the tire shop.

The shop pulled the tire to inspect it and found the puncture, which had made by a piece of fairly thick sheet metal (i.e., thicker than a tin can, maybe 1/16" thick) about 3/4" long, 1/2" wide, and shaped like the blade of a box cutter or X-Acto knife, sharply pointed but without a sharpened edge. The piece of metal was in the very middle of the tire tread, sticking straight in, point first, and had been worn down and was not sticking above the tread itself. Very odd, so maybe it was vandalism (but probably just my bad luck). In any event, the shop removed the metal, patched the hole, and remounted the tire on the car. So far it's holding air.

Despite all of this, I'm still not interested in getting a spare, in part because of the room it would take up in the trunk and because there ain't no way I'm going to change it myself should I have another flat. I did, however, buy a compact 12-volt tire pump to keep in the trunk along with a can of Fix-A-Flat (I know, I know) in case I'm in a spot where I can't reach AAA, etc. But I'm not considering going back to RFTs. Yet. 😉

Here's Tire Rack's rating of the 4S tires, which handle great, ride very nicely, and give me good feedback:

 

when I purchased my 06 SC430, it came with Dunlop RFT’s and rode horribly. After 3 or 4 years, I had enough and purchased Michelin A/S. I purchased a donut spare to use when I went on long trips to upstate NY to visit my wife’s sister’s. Kept it wrapped in the back seat where no one sat anyway. Otherwise, it was kept in the garage.

 

Your allusion to Fred Flintstone's rock wheels is - sadly - perfectly apt.

Did the non-RFT tires mitigate the road vibrations and did they improve the noise?

 

I’m sold on the Michelin Primacy Run Flats. They ride great and low road noise. Just replaced the Goodyear rft and a world of difference. Hopefully I’ll get at least 30k miles out of them.

 

Yes on both accounts. Handling is much improved, too.

 

I've done the same when I've had a cracked rim. I have some Ryobi tools, so their air pump for their 18 volt line like is just $30 without the battery. I guess with the cold temperatures, the ice sealed up the leak somewhat as I only had to fill it up every few days. Once it warmed up, I had to fill it each day.

https://www.homedepot.com/p/RYOBI-18...P737/206159256

 

Is there any difference between the Michelin Primacy Run Flats purchased from the dealer and those purchased at a tire store? The dealer's service tech tried to tell me the OEM models were better suited to my car. Any thoughts appreciated.

 

Compare the Michelin part numbers (not tire size). If they are the same the tire will be the same.

 

Just my $.02:

When I owned a Audi A8L I had it in for service. I noticed in the parts department several flats of new tires - between 40 and 80 new tires. Clearly marked on each flat was "TIRE RACK".

So to answer your question, ua549 is 100% correct: there is no difference exempt in the price you will pay!

 

Yes and no - there are MO spec tires as well as non-MO spec - Tirerack sells both. Depending on the model, the MO spec tend to run narrower in tread width at the same tire size. The OE manufacturers (BMW, MB, Audi, Jag, GM etc...) all have their own specification on certain tire models.

With that being said, I tend not to spec MO tires as the PS4S for my E63S4S are wider in the non-OE specification.

 

Thanks for the cautionary tale. I have no issues whatsoever with the ride or handling of the Pirelli Cintauro's that came stock on my E450 or the Michelin's that came on our E400.

 

Absolutely agree on the Pirelli tires. I. have the exact set of tires on my E450 CAB and the are surprisingly smooth and handle very well.....and I hate RF tires in general. These rf's have come a long way.

 

Yes, RFT's have come a long way. I appreciate the safety the most, but ride comfort, imho, hasn't suffered a bit with these tires.

 

Residents of cities with crappy roads tend to have negative opinions about rf tires.

 

That's true, no doubt.

Suspension/ shock absorbtion is primarily the tires' job. My experience (in northeast) is that all the little tar lines, patches, scrubbier pavement, etc. don't really transmit all the way to the suspension with a nice soft walled NRFT. They do more with RFT's. These small shocks are not enough force to use/activate/compress the car's suspension, so end up traveling thru it.

When I hit bigger "suspension" bumps (vs. "tire" bumps) it's clear what they are- my mind doesn't expect the car to go over it smoothly- so maybe I slow down a bit or something unconsciously or just accept it more unconsciously. (Or rather, it's clearly not unconscious in my case, )

It's the taught suspension/ soft tire combination that for me gives the best feel of that "stick to the road", planted feeling. (As a side note, the road bike world has been doing similar things with ever stiffer forks/chainstays, but preferring bigger, softer tires at lower pressures- even discovering that rolling resistance and efficiency don't suffer, while rider fatigue can be improved. Different is that this also actually decreases the likelihood of flats, because of more air volume in the tire, so less chance of a rim/sharp edge "snakebite" puncture. Less of a concern that object punctures in most cars.)

On perfectly smooth pavement I can't tell a difference. On bigger bumpier roads, I know it's a bump so don't expect the car to be completely smooth regardless (on a bike I'd lift out of the saddle just a bit to let my legs absorb the shock.) It's that in between stuff that I feel like is 95% of roads/my time in the car that I prefer the NRFT's for. I suppose it's also true that my cycling gives me a habit of looking at pavement closely.

Admittedly, I have not tried all RFT's and hope they are improving. However, for my personal preferences - theoretically (without a very different cross section profile) I don't see how they can or will make a sidewall both stiff enough to run flat for long enough, but resilient enough to absorb the small bumps at speed when not flat. Puncture resistance has gotten so good regardless my risk calculation has both a low probability and low consequence. It's been a long time since I have had a true flat, and I'm good with a fix a flat or wait for roadside where I live.

 

Here is your proof, they are a 1/2” thick

 

My wife has nail right in the middle of the Goodyear RFT. If you had to have a nail, it couldn’t be in a better spot. The Goodyear tire dealer nearby said they will fix it. Normally, they fix these things as a free compliment. Not in this case. They won’t be able to fix it until Thursday and she needs to use it for very local trips to the doctor before then. Tire seems to be holding the pressure, though I will check it every morning before I leave until then.

Selected Tire Manufacturer's Policies for Run-Flat Tire Repair

The following list summarizes tire manufacturers' run-flat tire repair policies, however it should be noted that every tire manufacturer that consents to repair, does so only after the punctured tire has passed a thorough exterior and interior examination.

Manufacturer/BrandRepair PolicyAdditional Provisions

BFGoodrichPermitted1 repair maximum

BridgestonePermittedOnly if 15 psi maintained

ContinentalDoes not recommendMfg. Road Hazard Program*

DunlopPermitted1 repair maximum for H- and greater speed ratings

FirestonePermittedOnly if 15 psi maintained

GoodyearPermitted1 repair maximum for H- and greater speed ratings

HankookPermitted

KumhoPermitted

MichelinPermitted1 repair maximum

PirelliNot endorsedMfg. Road Hazard Program**

YokohamaNot to be repaired if run-flat

*Replaced free of charge first year or first 2/32" of wear (whichever comes first). Continental advises that a repair to one of its tires invalidates all other manufacturer's warranties.
**Replaced free of charge first year or first 2/32" of wear (whichever comes first), then prorated until worn to 2/32" of remaining tread depth.


Tire manufacturers' policies for non run-flat tire repair can be found here: Flat Tire Repairs' Effect on Speed Rating

Use of run-flat tires deemed non-repairable may result in vehicle or property damage, as well as can cause personal injury or death.

Tire Rack will not repair any run-flat tires that have been driven in a severely underinflated or zero pressure condition because the service conditions they experienced and integrity of their internal structure cannot be confirmed.

 

Just fyi, you might want to reconsider using Fix-A-Flat. It wrecks the TPMS in the wheel. Even though Fix-A-Flat says it is fine to use on wheels with TPMS, the stuff will destroy the sensor. Having said that, what other choice do you have? Non-RFT with no spare means you'll need something to patch a puncture. Fix-A-Flat can save the day. But when you get to the tire shop to patch that hole, you'll most likely be forking out for a new TPMS unit as well.

 

You make a valid point, but it's something I was aware of. The Fix-A-Flat goop is simply my last line of defense, and like the Maginot Line, that plan has its flaws. As I said, I have AAA Premier coverage as well as roadside assistance through my auto insurance. That's Plan No. 1 should I have a blowout. Plan 2 is the tire pump, which will get me by for minor punctures such as the one that I described. Plan 3 is the Fix-A-Flat, assuming the tire is in good enough shape to be "fixed" but too badly punctured for the pump to be effective. Which brings me back to Plan No. 1. As for the cost, I'm fabulously wealthy and money means nothing to me!

 

anybody have any good ideas on how to test out a pair of non rfts before commitment? Would really like to try out on my front before purchasing, then realizing they didn't really make a difference??

 

Luckily, the nail didn’t puncture the tire. The next day, I realized the tire place increased the tire pressure to over 40 psi in that tire. I lowered it to the normal 33 psi. Yesterday, the tire pressure sensor warned about the much lower pressure in what was thought of as the affected tire. Turns out that tire was still fine but the other 3 were increased as well to over 40 psi creating an imbalance with the left rear. I lowered the psi to 33 for all once it cooled off. Are these people who fix tires idiots? Work on that one tire! Why are you messing around with the others? Really pissed me off. Unfortunately, they are the only ones in this area who would work on fixing RFT’s. It’s my wife’s car so I’m not in it every day. She’s the one who brought it in. Now I always have to check.

 

Well what brand were you going to settle on? Most tire brands like Michelin, Goodyear or Continental have 30 or 60 day trial warranties so if you're not happy, you can return them.

https://www.michelinman.com/US/en/tires/warranty.html

https://www.continentaltire.com/warranty

https://www.goodyear.com/en-US/tire-.../30-day-pledge

 

oh that's great news, so its like a satisfaction guarantee? haha i was even thinking about keeping my current runflats in the rear and then just replacing the front with something compatible, will lessen my chances of getting a flat tire on 2 non run flats only ! haha.
I have around 12 months left on my lease so might be lucky. Also will keep the 2 run flats and replace back before returning the lease.

 

I believe the only drawback is that you might be stuck with a particular tire line if you don't like the tires, but maybe if you go to a store like Costco that stocks multiple brands, you could end up trying a different brand. I think if you read the Goodyear one, they let you pick another Goodyear brand but that won't do you any good if you want some other brand.

 

The largest factor with the comfort of the tires is going to be whether its a "Ultra high Performance" tire like a goodyear eagle sport or whether it's more of a comfort tire like the "michelin primacy" which is categorized as a grand touring tire. Run flats have got much better over the past few years. Also you are not suppose to mix different tires from front to back, should be same tires on all four wheels as every tire has different type of tire has different handling characteristics. Could make you more likely to crash especially in a emergency situation.