[thakid22]

Originally Posted by chaungo

Going from RFT to Non-RFT will shave weight off of rotational mass.

That right there will already provide more benefits than having RFTs. I've had way better gas mileage, comfort and the car was alot faster as well.

Don't misunderstand me. I despise rft tires. I think rfts have ruined BMWs once fabled and legendary ride/handling mix. BMW now designs the suspension/steering systems calibrated for the stiff run flat tires. When you take the run flats off, there will be consequences.
It all depends on how much you value certain traits and also what tire you replace the rfts with.

That being said, I have removed the rfts from my, and my family members BMWs. I value the better ride more than the lost sharpness. At least I thought I did. I will definitely leave nonrfts on my mother's 5 series. The ride is smoother and she will NEVER notice the lost precision. But I just may go back to rfts on my own 5 series. Because I do miss that sharpness.
I originally posted because it was said that go flats were superior in every way. Not true at all.
The rfts have benefits as do the go flats.

I LOVE the more civilized ride of the go flats. I love their ability to track/corner better on bumpy or rough pavement. I HATE the loss of steering precision that accompany the go flats though.

[thakid22]

Originally Posted by rolltidef32

I definitely appreciate your analysis and prospective, but I've never heard anyone else say such.

Ah! That is the difference. I am not basing this on what I have "heard." I am giving you my real world experience on this topic.

I fell into the same trap... I researched the rft non rft issue. A quick browse of the forums revealed post after post of people declaring that run flats ruin the car and swapping them out for regular tires was a win win situation.

It was repeated on the forums so frequently that I just assumed it to be true. Even magazine "experts" said the same. Imagine my surprise when I made the actual switch and found out that it wasn't actually vice free! That is why I discuss this topic with such zeal. I don't want anyone to make the mistake I made... Thinking that rfts are all bad, and then lamenting the loss of precision after ditching them.

I am not saying I like rfts. I think it was a horrible move by BMW to force these contraptions upon us. My current BMWs all have the rfts switched out with appropriate goflats.
But there are specific changes BMW designed into the rft cars...
RFT necessitate softer bushings, revised strut valving, and I think a slower steering ratio to prevent the car from being (relatively) darty.

Now when all of those systems are designed for stiff (and quick/direct acting) tires, but then instead run on standard tires, there is a definite loss of sharpness. In the ride, the handling, and composure...

I'm on my cell phone right now. Give me a minute to grap my laptop. I'll come back and repost real world experiences from experts and novices who noticed the steering change.
You are right, most of us haven't heard of the downside of goflats on a rft car. That is a problem, because there definitely is a downside for those who value precision.

[thakid22]

Originally Posted by rolltidef32

I definitely appreciate your analysis and prospective, but I've never heard anyone else say such.

I know several professional drivers, including 2 who are BMW pro drivers/instructors, and none like a tire with that is stiff unless you're on a fast track where speeds can climb to over 140mph on a straight.

You can train yourself to drive on either, just have to control for it as other factors of the car, but again, your prospective is appreciated and gives something to think about.

http://www.tirerack.com/tires/tests/...nza+EL42+RFT_1

Here, TireRack tests the RE960AS Bridgestone RFT against its non runflat twin version of the same tire. An excerpt of what they had to say:

"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."

[thakid22]

Originally Posted by rolltidef32

I definitely appreciate your analysis and prospective, but I've never heard anyone else say such.

I know several professional drivers, including 2 who are BMW pro drivers/instructors, and none like a tire with that is stiff unless you're on a fast track where speeds can climb to over 140mph on a straight.

You can train yourself to drive on either, just have to control for it as other factors of the car, but again, your prospective is appreciated and gives something to think about.

http://www.bmwblog.com/2009/03/12/re...s-on-your-bmw/

This one is a quote from BMW, courtesy of the enthusiast group @ BMWBlog:

"All of our vehicles that use Run-flat technology have their suspension and braking components set up to accommodate Run-flat tyres. Should you decide to change to non Run-flats, it may alter the driving and handling characteristics of your vehicle. It is for this reason that this modification is not recommended by BMW as a manufacturer."

[thakid22]

Originally Posted by rolltidef32

I definitely appreciate your analysis and prospective, but I've never heard anyone else say such.

I know several professional drivers, including 2 who are BMW pro drivers/instructors, and none like a tire with that is stiff unless you're on a fast track where speeds can climb to over 140mph on a straight.

You can train yourself to drive on either, just have to control for it as other factors of the car, but again, your prospective is appreciated and gives something to think about.

Here is a quote from a fellow E90 driver who switched from the OEM Bridgestone Re050 RFT to Michelin PS2 non runflats...


http://www.e90post.com/forums/showthread.php?t=345740

"Originally Posted by ni8shadow View Post

So regular tires don't have a "performance" feel since they are "bouncy and soft?"

The RFT's have stiffer sidewalls to support the weight of the car without air pressure. This contributes to excellent steering response because they hold their shape better (they don't deform as much) when you turn the car. It also contributes to a rough ride on rough roads (because they don't deform as much). And they are also heavier. My RFT's were 6 pounds heavier than the Michelin PS2's (per tire).

When I first changed to the PS2's, I missed the excellent steering response the RFT's provided. Now that I've had the PS2's for a while, they seem fine. All new tires feel softer/mushier when they are new because they have more tread than the tires you are replacing and they need a break-in period.

The bottom line is that you give up some steering response to get a tire that rides MUCH better. If I drove on roads like they have in Germany, I would have kept the RFT's, but given the horrible roads many of us drive in the US, the trade-off is a good one."

[thakid22]

Originally Posted by rolltidef32

I definitely appreciate your analysis and prospective, but I've never heard anyone else say such.

I know several professional drivers, including 2 who are BMW pro drivers/instructors, and none like a tire with that is stiff unless you're on a fast track where speeds can climb to over 140mph on a straight.

You can train yourself to drive on either, just have to control for it as other factors of the car, but again, your prospective is appreciated and gives something to think about.

http://www.pistonheads.com/gassing/topic.asp?t=864844

Heres an E61 (5-Series Wagon) Owner who noticed the increased body roll with non runflats:


"OK i checked out all the posts on PH and it seems pretty much agreed that swapping the factory supplied runflats for non runflats is a perfectly OK thing to do. Potentially getting a smoother ride and saving about 30% on the cost of tyre replacements, so that's what i done.. However.... I have only swapped the rears (for a-symentrical Michelin Eagle F1's) with the fronts still being runflats (Michelin NCT 5's).

At the same time I has the tracking fixed as it was way out on the rear and OK, but still out on the front. This also resulted in my off center steering wheel now being nicely centered. All was good off I drove into the sunset.

The thing is now the car has significantly more body roll than before. The wife noticed it straight off and said it felt unsafe without me mentioning I had picked up on any change.

Anyhow I am unsure where to go from here. Based on previous searched the concept of using non-runflats seems sound, but do I now have to swap the fronts as well? Should I get the tracking/pressures checked???

I've got 32psi rear and 30psi front.

i'm thinking now though that those quoted pressures on the door shut are for RF's so maybe they need to be tweaked..

Any tips on suggested tyre pressures, or simply if it's a bad idea to mix the tyre types would be very much appreciated,

Cheers smile"

[thakid22]

Originally Posted by aw328i_NJ

Can you give more details on both your setups? Wheel and tire size. Thanks

Yes. This was on my factory 18" staggered wheels. This is on my 535i Sport Package. 245/40/18 front and 275/35/18 rear. Due to an unrelated issue, I ran both the PS2 ZP runflat and the PSS non runflat back to back. Same car. Same wheels.

On my E90, I went from the OEM semi worn 225/40/18 and 255/35/18 Potenza Re050 runflats to new Goodyear Eagle Sport non runflats. Only in that instance, the change (loss of precision) was more dramatic due to the fact I not only went from rft to non rft, but the Eagle Sport was an All Season tire too, not a summer like OEM. The OEM rft, had steering almost like a go cart. On the freeway, a sneeze (and corresponding twitch of the steering wheel) would make the car dart slightly in its lane. The non runflats relaxed the steering but made it less laser sharp there too.

[thakid22]

Originally Posted by rolltidef32

I definitely appreciate your analysis and prospective, but I've never heard anyone else say such.

I know several professional drivers, including 2 who are BMW pro drivers/instructors, and none like a tire with that is stiff unless you're on a fast track where speeds can climb to over 140mph on a straight.

You can train yourself to drive on either, just have to control for it as other factors of the car, but again, your prospective is appreciated and gives something to think about.

So. There you have it. From multiple sources...
You will easily find more on your own if so inclined. But EVERYTHING I have said is well documented by those who actually make the switch.
As for rft vs non rft, you just have to know the right questions to ask.
I (initially) did not. Most conversations revolve around ride quality and NVH. You'll also hear about how non rfts handle better. And they do! In certain situations. The extra compliance increases grip and stability greatly on less than perfect roads. But the down side is that the steering will be less direct, slower, and on center feel and effort ramp up can weaken.

Think about it. For a moment, forget spring rate, shock valving, etc. Think of each corner as an assembly. Each corner has its own wheel rate, the rate at which the bushings/mounts/tires/springs/rim/shocks, etc all cumulatively operate. A rft can be up to 35 % stiffer than a conventional tire. Swapping it with a softer tire is somewhat similar to swapping in softer shocks/bushings/springs etc. The overall wheel rate drops.

Lower wheel rate can produce a smoother and quiet ride, but can and will also reduce control and response.

E90s were designed around early runflats that were stiffer than todays models. Adding non rfts to those cars evoked a night and day difference. They took on a smoother, more civilized, but almost underdamped demeanor on non rfts. Today's F-Series BMW makes less concessions owed to its new generation, softer (but still stiff) rfts.

Again, I'm not advocating runflats. I wish BMW had left them off of the spec sheet. The rfts are now an integral part of the BMW chassis. Those rfts do impart a sense of sportiness. BMW knows they are stiff. Consequently, stiffness has been removed and added from/to various other chassis parts to accommodate that. Throw away the rft stiffness and the car is left without a bit of stiffness that it once used.

The steering is a perfect example. With reduced sidewall flex it literally takes less steering angle (especially initially) to turn the car. Go flats increase flex and also the required steering angle for a given turn. It is very obvious when you are looking for it, especially if you can drive to cars back to back (rft vs nrft).

All that being said, go flats are not gonna destroy the handling precision of these cars. They will dull it every so slightly. Some may never even notice.
In the end it can argued that go flats give MORE in traction and nvh, than they take away from precision.

I hope I have been able to help and perhaps save someone the shock I experienced.

On another note, uh - I know I'm getting long winded, the current crop of RFT are much less of a NVH compromise than they used to be.

The Michelin PS2 ZP runflat was nearly as civilized as the PSS nonrft I replaced them with. In fact, they felt like a sportier version of the same tire, around town. Quiet, firm, and responsive. I do feel that the PSS did have better ultimate grip though. Anyway, I've strayed from the original topic...

[rolltidef32]

Originally Posted by thakid22

http://www.pistonheads.com/gassing/topic.asp?t=864844

Heres an E61 (5-Series Wagon) Owner who noticed the increased body roll with non runflats:


"OK i checked out all the posts on PH and it seems pretty much agreed that swapping the factory supplied runflats for non runflats is a perfectly OK thing to do. Potentially getting a smoother ride and saving about 30% on the cost of tyre replacements, so that's what i done.. However.... I have only swapped the rears (for a-symentrical Michelin Eagle F1's) with the fronts still being runflats (Michelin NCT 5's).

At the same time I has the tracking fixed as it was way out on the rear and OK, but still out on the front. This also resulted in my off center steering wheel now being nicely centered. All was good off I drove into the sunset.

The thing is now the car has significantly more body roll than before. The wife noticed it straight off and said it felt unsafe without me mentioning I had picked up on any change.

Anyhow I am unsure where to go from here. Based on previous searched the concept of using non-runflats seems sound, but do I now have to swap the fronts as well? Should I get the tracking/pressures checked???

I've got 32psi rear and 30psi front.

i'm thinking now though that those quoted pressures on the door shut are for RF's so maybe they need to be tweaked..

Any tips on suggested tyre pressures, or simply if it's a bad idea to mix the tyre types would be very much appreciated,

Cheers smile"

I have a staggered 19 setup with a recommended psi of 32 f/r. For go flats, this is not enough pressure, so I raised my psi to compensate for a softer tire. I run 33psi Front and 35psi rear.

Adjusting psi is important. From that quote, not sure I've ever run as low as 30psi on any set up.

[xxxjecxxx2]

Originally Posted by MickAv8r

My brain immediately went here:

Your tire guru... isn't.

I watched that youtube video. Then I clicked on a recommend one after. I forgot how I got there then I saw this post. Thanks a lot.

[thakid22]

Originally Posted by rolltidef32

I have a staggered 19 setup with a recommended psi of 32 f/r. For go flats, this is not enough pressure, so I raised my psi to compensate for a softer tire. I run 33psi Front and 35psi rear.

Adjusting psi is important. From that quote, not sure I've ever run as low as 30psi on any set up.

I agree. BMW typically have relatively firm suspensions. I have found that adjusting psi can fine tune feel, if you need to.

I see you are running PSS (your sig). I found the PSS very happy at around 35psi too.

BMW says runflat/nonflat configurations should use the same pressure. Seems weird to my mind. Typically though, I use the recommended psi as a starting point and adjust up or down as I deem necessary. 30psi seems low, but that's what some of those E60 called for.

[black_F10M5]

Originally Posted by thakid22

Yes. This was on my factory 18" staggered wheels. This is on my 535i Sport Package. 245/40/18 front and 275/35/18 rear. Due to an unrelated issue, I ran both the PS2 ZP runflat and the PSS non runflat back to back. Same car. Same wheels.

On my E90, I went from the OEM semi worn 225/40/18 and 255/35/18 Potenza Re050 runflats to new Goodyear Eagle Sport non runflats. Only in that instance, the change (loss of precision) was more dramatic due to the fact I not only went from rft to non rft, but the Eagle Sport was an All Season tire too, not a summer like OEM. The OEM rft, had steering almost like a go cart. On the freeway, a sneeze (and corresponding twitch of the steering wheel) would make the car dart slightly in its lane. The non runflats relaxed the steering but made it less laser sharp there too.

Thanks for your input, appreciated!

I have been thinking of doing a 18x8.5 square setup with a 245/40 tire. Lucky enough Michelin does offer a few runflat options in that exact size. I may do the A/S version though since I do not want to have to swap summer tires out in the winter

[beanbaguk]

Another one here did the non-RFT swap.

I had a set of Goodyear Asymmetric 2's installed all round (at protest from the tyre dealer as they were marked "Recommended for Mercedes", which as you all know means sweet FA).

The tyres are a marked improvement from the standard Goodyear EfficientGrip's that came standard on my 18" rims, but I will agree there's a bit of "wallow" on sharper corners. Much of this could probably be fixed with some suspension tuning but that's only if I really push it and I rarely do.

Also, RFT's are notorious for damaging rims as they don't offer any give and won't distort on pot-holes.

Anyway, the car is now much quieter and handles beautifully for most driving conditions.

It's a shame however the tyre shop that installed the tyres scratched every rim, did not balance my tyres properly and mis-aligned my car and accused me of misinforming them of the model of my car. (The moron manager told me my car wasn't an F31, but an E91!!!).

The consequence was a US$340 repair bill at my BMW dealer. I'm currently taking the tyre shop to the small claims court to re-coup the cost of these repairs as they only offered me $150 as a "good-will" gesture. I told them to stick their goodwill up their arse and enjoy a letter from my lawyer.

Sadly however in Spain, lawyers take more coffee and shit breaks than any other profession I know so it'll be months before I get this money back.

[IllLojik]

Originally Posted by thakid22

So. There you have it. From multiple sources...
....

Thanks for that well put analysis. I was beginning to feel as if I'm the only one that noticed that my RFTs handled better precision wise. I noticed this when I had my e90 on non RTFs. I was losing my mind trying to figure out why my BMW didn't feel as sharp. Don't get me wrong, I was happy with the other improvements, mainly comfort and less noise and weight. The Bridgestone Efficientgrip tires that came with my f30 are actually more on the comfortable side of RTFs to believe it or not so I'm not as in a rush to get rid of them.

Either way, your analysis is on point with my experiences between the two types.

[oceanview]

When looking at a tire comparison like RFT/non-RFT it is also important realize that a tire is available with different load index.
The 225/45 19" 89Y can handle 580 Kilogramm per tire
The 225/45 19" 93W can handle 650 Kilogramm per tire (mostly also marked with "XL" for extra load)
XL normally has a stiffer sidewall and therefore a stiffer feeling.

Any tire has to match the weight of the car. So normally for every car you have two tire variants available: Standard or XL

I started to use XL on my non-RFT setups many years ago, because I like the less spongy feeling compared to the standard load index variant.
(I use XL this for front and rear axle tires, on summer and winter tires)

Steering response is also very depending on tire profile and the rubber compound used. That's why in tire tests-reviews tires get different rates for steering response, on the same kind of tires.
So comparing RFT with non-RFT only gives a 1:1 result when looking at the same tire type/profile.

When reading professional RFT non-RFT test reviews, the result is, that non-RFT are easier to control in under-/oversteering situations.
Non-RFT have better lap time in wet conditions, but RFT have better lap time in dry conditions.
Non-RFT have much shorter braking distance (60-0 mph almost 1 car length)
Test was done with an E90 330i.

So there is pro and cons for everything. And as technology improves also on RFT, I will review my non-RFT decision the next time I need new tires.

[DerekS]

Originally Posted by xdnbc

My tire guru told me that BMW with RFT have flatter camber and less caster- so they stay square on the road when flat. With regular tires, camber should be added for cornering. This is my first BMW and I tried to buy the car without RFT and they would not trade tires. The fact that these tires can go 80km at 80 kph doesn't help at all because if I am on a trip and get a flat, who is going to have a replacement tire that matches what I have within 80 km- and replacements in Canada are over $600 incl. mounting and balancing. So now I am paranoid about going on long trips with my new wagon.

For long distance travel to remote areas, I would suggest that you carry a mounted spare (snow) tire, along with appropriate tools to exchange a flat tire, in case your Tirefit kit (Plan A) did not solve the problem.

[gestut]

Originally Posted by thakid22

Go flats are NOT battery in EVERY aspect.
No doubt, they have their benefits. Grip, ride quality and and rough road adhesion all improved dramatically when I fitted go flats. I went from Michelin Pilot Sport ZP RFTs to Michelin Pilot Super Sport non run flats. Three things immediately were evident.
1. The run flats had sharper steering feel. That is, smaller movements at the wheel provided greater immediacy in vehicle response. Very noticeable on center but also while negotiating turns around town. The higher the vehicle speed, the more noticeable this was.

2. Steering Effort was slightly greater at all times with the run flats. The RFTs had a more immediate ramp up of resistance when beginning to turn the wheel left or right.

3. Body roll, and Brake dive were less on the RFTs. During brisk corners the increased sidewall rollover is perceived as an increase in body roll from inside the car. Brake dive. The last second of a stop evoked a bit of additional rocking from the vehicle as the car comes to rest on non-rfts. This feels like extra dive and squat. Watch a car stop briskly, you can see the front tires flatten and the rear tires uncompress when the car comes to rest. The RFTs stiffer sidewalls resist this motion better.

I will say that some of these things are very subtle. The average driver will never notice. They'll feel the softer ride of the goflats and never miss the sharper (not necessarily more capable) handling of the RFTs. In that case great! But, I did detect and lament the loss of a bit of precision when switching from run flats.

In my case, I went from new PS2 ZP to new PSS non runflat and can honestly say both tires had their merits. One did not dominate the other in "all" areas.


I'd equate the increase in sharpness with the RFTs to be VERY similar to adding polyurethane control arm bushings up front. It is the type of feel that you get from going from stock E90 control arms to E90 M3 arms.

Just want everyone to know that the swap to goflats is NOT without consequence. A more accurate assessment would be that MOST people will completely satisfied with go flats, and will not miss the run flats at all. But I'd like picky (or extra sensitive) people to know that, as usual, installing softer suspension/wheel components (non RFTs in this case) will be accompanied by the usual reduction in precision. Some may notice, some may not. That is debatable. But the reduction will be there.

I just ditched my rft and got PSS, and wow did I notice everything you said above. I thought i was crazy. the steering response was immediately noticeable on non rft. It didnt feel razor sharp like the rft. feels like the car is slower in lane changing then it was, kind of disappointed actually. I am sure it has better grip. what pressure did you end up running , i have the staggered wheels/19. i increased it to 42 on all corners , its still not the same as rft though

[Red_Baron]

I have a 340i with the track and handling package with the 18" non-runflat Pilot Super Sports.

In anticipation of winter's cold and wet, I bought a used set of 403M 19" wheels mounted with Pirelli summer run-flat tires. The 403M wheels will get snow tires in a couple months.

This puts me a position to comment on the topic of the thread from first hand experience. Here are my thoughts.

run flat 19" Pirellis summer tires:

• harsh ride even in Comfort with bumps
• good absolute grip
• quick steering changes (this agrees with the quicker steering comments)
• no obvious indication of loosing grip leading to
• aggressive stability control intervention
• lower driver confidence
• no fun...I really dislike these tires

Go flat 18" Pilot Super Sports:

• great grip
• good feedback of the available grip leading to
• much better steering feel and
• great driver confidence and
• predictable handling and fewer perceived stability control interventions
• very comfortable ride even in sport damping settings and no harsh jolts from road imperfections
• very fun to drive...I will buy another set when these wear out

[F32Fleet]

Originally Posted by thakid22

Don't misunderstand me. I despise rft tires. I think rfts have ruined BMWs once fabled and legendary ride/handling mix. BMW now designs the suspension/steering systems calibrated for the stiff run flat tires. When you take the run flats off, there will be consequences.
It all depends on how much you value certain traits and also what tire you replace the rfts with.

That being said, I have removed the rfts from my, and my family members BMWs. I value the better ride more than the lost sharpness. At least I thought I did. I will definitely leave nonrfts on my mother's 5 series. The ride is smoother and she will NEVER notice the lost precision. But I just may go back to rfts on my own 5 series. Because I do miss that sharpness.
I originally posted because it was said that go flats were superior in every way. Not true at all.
The rfts have benefits as do the go flats.

I LOVE the more civilized ride of the go flats. I love their ability to track/corner better on bumpy or rough pavement. I HATE the loss of steering precision that accompany the go flats though.

+1.

People who go non-rft ignore the fact that the stock alignment for their vehicle was done with runflats in mind.

For the record my wife has non-rft S001's on her vehicle and I really don't notice much of a difference when compared with my RF S001.

I also second your comments about the trade-offs associated with going non-rft. People will look for any reason to justify their decision to stray from whatever the manufacture recommends.

[lesBray]

RE car geometry designed for run flats. When speccing my car there was and is currently an option for 18" V-spoke Orbit Grey Style 398 alloy wheels these do not have run flats or at least no all or them are run flats. That was the reason I was considering them. So maybe steering geometry is not just for run flats.
I decided against them as I didn't like the look of them on the configurator and couldn't see any in real life to know for sure. If I could have seen them for real and thought they didn't look awful I would have gone for them to avoid having run flats. Lower unsprung weight and softer side walls sound a good idea to me. However I chose the LA wheel, M double spoke 441 18" that come with Bridgestone Potenza run flats. They are very highly rated by testers but they are very sensitive to tyre pressures. At the lower end of recommended pressure for the tyre size the car was nervous in a straight line at moderately high speed, I would say verging on dangerous at properly high speed. Feels similar to driving with worn dampers very sensitive to side winds though changing the adaptive M sport damper setting to sport made no difference. Pressures at the very highest of recommendation (the five person pressure on the sticker) straight line stability is transformed and becomes very assured. Car remains supremely comfortable. I definitely wouldn't recommend any one running these at anything less than the highest recommended setting. It seems very high if I remember correctly its something like 42 and 48psi. Beemer back at the dealers at the mo so cant take a look at the sticker.
Some here are saying run flats have ruined the ride handling mix of the 3 series. Very tidy handling and comfort were 2 number 1 priorities for me in my choice of car. The BMW stood out as being supremely comfortable. I have not driven a more comfortable car. I have driven many current models. The seats with adjustable lumbar play they're part and also best in the business just takes some time to find the perfect setting with so many adjustments. I chose M Sport adaptive suspension despite warnings that this may detract for the comfort I raved about in the test car but the suspension choice was a good one. I don't see how anyone can claim that RunFlats have destroyed Comfort. Handling wise the car could be more communicative. Certainly 2 seater sports cars from Mercedes Audi or Porsche are much more communicative than the Beemer though perhaps thats an unfair comparison. More comparable the Quattro Audis certainly give the beemer a run for its money in terms of handling but none of those can match the comfort of the beemer. If run flats compromise the handling and comfort mix then its handling and specifically feel that is compromised not comfort.

[n00bim2015]

I agree with some of the sentiments of this thread. Regular tires on my bmw do seem like the turning feel is amiss. the runflats provided more stiffer feedback when turning from slow moving and mild speeds. although, i am losing the feel, or maybe the wear in of the tire is helping.

[Vitoco]

Going from RFT to non-RFT it is recommended you choose an XL version (You can even see the XL-variant on the recommended tyre pressure chart on the door sill).

Found this picture and basically on XL tires #4, which is the carcass, is reinforced to take up to 4 times higher than normal load.

Ditching the RFT´s was the best thing I did on the E90 and it has also been on this one.

How many of you that have commented here have chosen XL-tires when replacing the RFT´s?