Have Runflat Tires Finally Come of Age?

Sections: Accessories | Technology Dec 2nd, 2011 21 Comments

Ever since BMW made the switch to run flats, enthusiasts have been waiting patiently for the technology to mature. And with BMW’s move of course came MINI’s reliance on run flat technology as well. This is especially true in the US where they’re not an option (as they are in there markets) but standard on all tire sizes larger that 15″.

We’ve been waiting for the technology to become transparent – meaning that there’s no trade-off in feel, performance and comfort as compared to the tires we’re all used to. With the launch of the 3rd generation of run flats, tire makers – specifically Bridgestone – may have finally done it. Our friends at Tirerack recently tested the Bridgestone’s third generation run flat and came away very impressed with the results and the tech behind it all. Here’s an excerpt:

Bridgestone’s new third generation (3G) run-flat features a sidewall design that helps minimize the run-flat tire’s negative influence on ride comfort. While still thicker than a conventional tire, the signature features of the 3G run-flat sidewall are a unique exterior cooling fin design and special rubber compound, both designed to reduce the heat buildup that occurs while driving on a tire that is no longer inflated. Reduced heat buildup during run-flat operation allows for the thinner sidewall design, ultimately improving ride comfort.

Out on the road our team found the ride quality of the Potenza RE960AS Pole Position RFT run-flat tire to be very similar to the conventional Potenza RE960AS Pole Position, with a small advantage to the conventional version. The older-generation run-flat design in the Turanza EL42 RFT felt noticeably harsher when it encountered sharp-edged impacts both small and large, such as expansion joints, poorly patched pavement or minor potholes.

The conventional Potenza RE960AS also produced slightly less impact noise, with the 3G run-flat version very close behind. Again the older generation run-flat design of the Turanza EL42 RFT produced some additional booming as it hit bumps in the road.

The handling of the Potenza RE960AS 3G RFT was actually a little crisper than the non-run-flat version, taking advantage of its inherently stiffer sidewalls to help the tire change direction more briskly. The conventional Potenza RE960 was close behind, also feeling nimble and responsive. The Turanza EL42 RFT trailed the two Ultra High Performance All-Season tires, feeling somewhat less responsive as you would expect from a Standard Touring All-Season tire.

Many of our team commented on how similar the run-flat tire behaved to the conventional Potenza RE960AS Pole Position. They felt very little trade-off in everyday ride comfort and road manners when choosing the run-flat tire over the non run-flat version.

You can read the full test here. And keep in mind that the tire tested above is an all-season and not optimal for high performance warm weather driving.

Written By: Gabe

Joe Farace

Hating my Continental runflats on my 2012 Clubman S. Maybe these will work but I’m skeptical.
that.guy

There is a huge range in sidewall stiffness on conventional tires. I have not doubt they can engineer runflats to ride as well as conventional tires on the stiff (high-performance) end of the spectrum, but that’s only half the battle. I found the Dunlop Z1s I had rode pretty similarly to the runflats they replaced. Main difference was their kung fu grip and predictable break away. The older generation runflats rode stiff, had poor ultimate grip and handled poorly. That’s a tough sell.
vmmvmmm

Seems to me that all the recent reviews of BMW and BWM family cars have specific complaints about the runflat tires. I hated them when I had them, and that still seems to be the case. Would love for these to come of age, but I think it’s a promise the tire companies have not been able to come through on.
JonPD

Too me runflats are just a compromise. a little utility true but they try to be all season tires. To me summer tires and winter tires are very different creatures and there is no good single option.
Chris Underwood

Wonder how well their cooling fin holds up to curbs…
- Anonymous
  
  Maybe they will provide additional curb rash protection! :-P
Anonymous

Call me a skeptic. Are they cheaper than 2G run-flats? Do they have longer tread life? How much do they weigh?

I suspect they will still be too much of a compromise for me to ever consider. I have a set of brand new Dunlop run-flats from my JCW sitting in storage until summer comes around and I buy new tires.
- David
  
  Here’s to hoping there is not a 4G runflat anytime soon…
Anonymous

My car came with Pirelli Eufori@s and they were awful. AWFUL. I switched to Kuhmo Ecstas because they were cheaper. The ride was a tad better, but still abysmal. Back in February I finally bit the bullet and went with non-run-flats (after I got a mobility kit). My R53 is like a different car now. To be honest, the ride harshness wasn’t the worst part of having run-flats. What I couldn’t stand was the utter lack of reliability. There was no warranty whatsoever. Your tires could last 100 miles and the manufacturer would just say, “Sorry.” Exacerbating the issue was the exorbitant cost to replace them. The price of my OEM tires has come down: they’re now around $220 vs. $300 when I first got the car, but they’re not affordable by any measure. Until they can guarantee any sort of life, there’s no way I’m touching run-flats again.
“x”MINImofo

I ditched my runflats for 32″ BRGoodrich off-road tires that where attached to a 2012 Rubicon.
Beken

I found it odd that in longterm tests in the magazines, they had incidences where the tire needed to be changed. Myself, the two years I had runflats tires on my car, I had 4 flat tire incidences either punctures or air leaking out of the rim. Having had non-runflat tires on my MINI now for almost 4 years, I have yet to have a flat tire incidence. I am curious if the new generation is as fragile as the previous generation, or more so.
Gary

Another skeptic. I see the “cooling fins” as mostly a marketing gimmick with marginal effect, analogous to changing the number or shape of the dimples on a golf ball and touting how much further it flies. I suspect the ride may be better, but as Jon says they’re still a compromise. In any event, Tire Rack must be pleased with the additional (free?) web traffic this post has stimulated.
Gary

Another skeptic. I see the “cooling fins” as mostly a marketing gimmick with marginal effect, analogous to changing the number or shape of the dimples on a golf ball and touting how much further it flies. I suspect the ride may be better, but as Jon says they’re still a compromise. In any event, Tire Rack must be pleased with the additional (free?) web traffic this post has stimulated.
KPH

I’m just against the whole concept on principle and practicality. Design a car to somehow carry at least a donut spare and when you blow either type of tire to bits between Termo and Standish Ca. you’ll be on your way in 20 min. Destroy a RF, then check for a cell signal. Good luck. I hope it’s daylight and a nice comfortable day. Take this opportunity to enjoy the high desert scenery.
SFRedMCc

How about cost, tread life and repairability?

I had a sheet metal screw imbedded in a Goodyear Excellence 195/55R16 87H tire on my 2008 Clubman, and was told it couldn’t be repaired; and the cost of having it replaced was $371.

Also the other 3 remaining tires w/ 22K miles only have 4/32″ of tread left; and I was told they are due for replacement.
Hemisedan

Last year I ditched my RF’s to Michelin ICE then in the Spring traded off to Hankook summer tires. Best thing that I’f done, Tiresias in a long time. No problems, no flat tires. I figure that is what the tire pressure warning light is for. As for the ride, it’s all right, nothing fantastic, but better than my wife’s Jeep. But, when I had the Summer tires taken off last month, there was a scew in the tread. Never knew anything about it. I don’t carry a spare, no compressor kit, no repair kit. Just drive it and have fun with my black & red 2011 JCW hatchback.
Mabels1126

Sounds likr RF’s are gonna need better PR.
http://twitter.com/ichibut Wayne Dyer

Runflats have done more for improving profitability in the tire industry than any other innovation, I expect. They’re a cash machine. I’m on conventionals right now with a pump, slime, and plug kit, just hoping I don’t run into anything
Dave

For the most part, seems a many of the RF ride complaints are by those who’s MINI’s have some mileage on them or those coming from another product line from Japan or Korea. And for those with 1st Gen MINI’s or older 07-09′s how many of those with complainants replaced their struts after 60/70 or 80K miles. These are not life time parts……

My JCW struts lasted less than two years about 38K miles.  While it may still corner pretty good the ride quality is hardly what it used to be. Now it’s harsh, hardly forgiving and at times teeth jarring and that is with a new set of Kumho Ecsta ASX….non-runflats.

Another issue with all RFT is their weight.   Good God – 29+lbs a tire is way too heavy IMO.  And these were originally designed to be used on cars running the Autobahn in the event of total tire failure as THEIR safetly feature. But considering we have a 55/65 MPH speed limit is it really necessary here ?

Somtimes when a company has a mission statement for the ultimate anything, they can become a bit myopic with their thinking. So did they factor in acutal “rolling resistence” of this tire ?

Increased weight difference and rolling resistence equals poor MPG’s…..something else for Bridgestone to consider….

Maybe they can forgo the costly front air bags to lower MSRP and instead just issue every MINI owner a helmet and head/neck straps ?
BMW13t

To the person that said run flats cannot be repaired I’ve had two repairs in my Clubman S Pirelli’s and one in my 335i Bridgestones so they can be repaired. If the screw hole was big enough to not be repaired it would have been the same results with a non run flat. One of the major car magazines (i can’t remember which one since I get them all) recently tested the same tires on a BMW 328 and said they were great. I need new rubber on my 335i and will get the new Pole position AS 960 run flats.
Roger

Too bad none of the sizes that the Potenza comes in would properly fit a MINI . . . .

http://www.bridgestonetire.com/productdetails/QuickSearch/Potenza_RE960A/S_Pole_Position_RFT

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