Run flat vs non?

[1addict]

The debate continues.....I have heard that BMW's that are with OEM run flats are set up a certain way that if you get nons you need to adjust your springs etc to have a better ride otherwise it will drive like crap? Anyone know if this is true or heard anything about it?

[mryakan]

It will drive different, but not necessarily like crap. Some people notice a softer/mushier ride, others don't even notice. It is down to $$ v.s. convenience.

[1addict]

with nons it would be softer because run flats are stiffer correct?

[samger2]

Yes that is correct. Any self supporting tire will have a really stiff sidewall. Like mryakan said, many people say the change in ride quality is much better.

Just make sure if you go to non-runflats you do something about the fact that you have no spare in the car.

[1addict]

Thanks. And what about performance? Do run flats handle better due to the stiff sidewall? I have V speed rated now, will I notice a difference if I get Z rated?

[mryakan]

Thanks. And what about performance? Do run flats handle better due to the stiff sidewall? I have V speed rated now, will I notice a difference if I get Z rated?

I believe Kevlar once posted a link to a test done on the track in which both runflat and non runflat equivalent performed almost identically. So as mentioned, it just comes down to cost vs convenience. Make sure you figure out your flat tire strategy before going to non-runflats though.

[1addict]

Thanks

[kiwi29]

personally i like non rf tires because they have more choices and it's alot cheaper, the comfort and handling difference isn't really noticed when you're driving (i.m.o.)

[apes]

Thought I could tag onto this thread. Need new tires and trying to decide if want to go away from run flats. I agree it is $$ v. convenience. I just went to price tires at local tire shop and found that difference in price may not be as much as I thought. Here is what I'm looking at and would like to get some feedback, as to tire quality and ride for the brands. I have 2007 BMW 335i convert, sport package. I drive highway and locally and my style is pretty easy going.
size 225/40R18
255/35R18
the run flat the guy offered was Kumho ECSTA SPT price 1075.00 all in 1226.00

non-run flat
Yokohama avid Envigor price 916 all in 1056.00
also, Nexen for 179.00/per tire

someone else showed me Falken tires, has anyone heard of these, non run flat about 1200.00.

After doing some research I'm leaning towards run flat (convenience) but possible upgrading the tire to Yokohama or Michelin which i know will get my cost up to the 1500.00. With run flats I want to get quietest ride possible and good wearability.
Thanks, i hope this was an appropriate post here.
if it matters I own a set of winter run flat tires.

[amtex]

At Tire Rack ran-flat tires are almost twice more expensive then non ran-flat.

[mryakan]

At Tire Rack ran-flat tires are almost twice more expensive then non ran-flat.

Not necessarily. It depends on the brand and size. Some are only 20% or less more. I'm on my 3rd or 4th RFT purchase.

[328isFanatic]

I believe the biggest difference between a RFT and non-RFT is a weight and vertical stiffness of the sidewall.

If you move from a factory RFT to non-RFT assuming you stay in the same tire category (say max performacne summer) you will find better ride quality with a non-RFT because of the lighter tire. For example a 225/45R17 Bridgestone Potenza RE050A is 22lbs for a non-RFT and 27lbs in run-flat. 5 lbs per tire is INSANE. Withe that, you should also see some improved handling characteristics.

To speak to your original question- I do not believe changing from a factory RFT to a non will make your car feel like crap. Although originally designed for the run-flat your suspension will be very happy with the lighter rubber. Changing the other direction from non-RFT to RFT will, however, make your car feel much much worse.

[Stratman335]

I just swapped my stock run flats for a set of kumho le sport otherwise known as model ku39 and here is what I noticed after 2 days.

Off the bat the tires are way lighter and the steering reflects that as well.
The ride is muuuuch more comfortable and I don't bite down on my lip and close my eyes when I hit a road imperfection as I used to.
It used to feel like the mags were taking a beating before but not now.

As for road noise, they're virtually silent as I can't hear them at any speed really.

Another significant change you will notice is kind of a less firm ride , almost as if the suspension was loosened slightly.
I personally noticed this when I performed a little test.
I would roll at like 20 and just kind of play with the steering wheel from right to left.

It feels as if ur getting slight body roll compared to before where I would get none.

I always thought it was due to a very stuff suspension but now I see that it was because of the run flats.

As for grip ... No comparison whatsoever
I get zero wheel hop and the tires grip much better and feel better in the rain as I had heard in some reviews that they were indeed great in those conditions.

I still have warranty and I don't think that calling BMW road side assistance or a tow truck is a steep price to pay for getting much better grip,comfort,quietness daily.

Yes run flats offer u the chance to keep driving while ur car has lost pressure due to a nail or screw like what happened to me but that definitely didn't make up for bad overall drive.
It literally felt like my tires were made of concrete.

It was the first time I ever had a car with run flats but it will definitely be my last

I mean don't get me wrong ... I like a nice stuff sporty ride but those bridgestones are absolutely terrible and u know what? Check the reviews they got on sites like tyrereviews.co.uk ,tire rack etc... And see what people rated them as and te comments they left.

They scored horribly ! They got an overall rating of 72% after 103 people reviewed them
Seems like most people were quite disgusted and shared my thoughts exactly.

If I lived in an area where the roads were absolutely perfect no matter where I went, I'd stick with the run flats but I don't and life was unbearable with them and I'm surprised my mags didn't crack yet like how so many others have had issues with.

The stock run flat tires don't absorb any of the shock of hitting a road imperfection and the force is directed into ur mag.

Normal tires will do a better job but u gotta remember that they're still low profile tires so they won't do much if u hit a big one.


Anyway I'm going to do some more testing when I get a chance on these tires and provide better comparisons in the next few days on the actual tires.

Hope this helps

[Magik]

"I just swapped my stock run flats for a set of kumho le sport otherwise known as model ku39 and here is what I noticed after 2 days.

Off the bat the tires are way lighter and the steering reflects that as well.
The ride is muuuuch more comfortable and I don't bite down on my lip and close my eyes when I hit a road imperfection as I used to..."

Mryakan, please comment on this. I have staggered pair of OEM Michelin Pilot Sport PS2 Runflat Tires (not Bridgestones) and anytime a I hit a tiny bump at moderate speed with the wheel minimally turned, the whole car shakes, rattles and rolls. And now I have to bite my lip

I though RFTs had stiffer sidewalls.

I also bought one of those "tire and wheel" package insurance from the dealership, that replace damaged tires/wheels with ONLY OEM products. So what OEM non-RFT should I consider trying next before I settle the age old question: RFT vs non-RFT!!

Thanks Stratman for the awesome review.

[mryakan]

Mryakan, please comment on this.

To each their own. I do not mind the runflats, but many do. Doesn't bother me. We don't all have to be the same.
That being said, I always advise people to make their own decisions by trying things out instead of being a sheep and following the internet herd blindly (no offense intended to anyone).

[04E60]

I'd rather just get non run flat since its cheaper, if you get a flat you get a flat no way around it, tire is messed up either way, and run flats can be patched up either.

[Magik]

To each their own. I do not mind the runflats, but many do. Doesn't bother me. We don't all have to be the same.
That being said, I always advise people to make their own decisions by trying things out instead of being a sheep and following the internet herd blindly (no offense intended to anyone).

I get that we should make their own decision but I'm specifically asking about transient loss of control whilst going over small bumps on corners. Is that due to the RFT's or it that common on all tires? That's really what I want feedback on. I don't want to switch to non-RFT only to find that this problem is inherent to all tires.

Thanks again for your help, Mrykan.

[mryakan]

I get that we should make their own decision but I'm specifically asking about transient loss of control whilst going over small bumps on corners. Is that due to the RFT's or it that common on all tires? That's really what I want feedback on. I don't want to switch to non-RFT only to find that this problem is inherent to all tires.

Thanks again for your help, Mrykan.

Not sure what you mean by loss of control. You do feel road imperfections a lot more, the stiffer sidewalls do exaggerate that, but wider tires do that too RFT or not. I've hit many potholes and never once felt I am not in control of the car, but the car does try to struggle out of control on bad roads. Used to even have that with 225/50/16 non runflats on e36. The alignment has something to do with it too.

[Magik]

I'm not refering to potholes per se but slight bumps. The car seems to lurch sideways in the natural direction as I take the corner, then regain control millisecs later. I never experienced this in my old 2006 civic si and was wondering if it was the RTF or issues inherent to a sporty rear wheel beast like the 335is. It sounds more like the latter.

[mryakan]

I'm not refering to potholes per se but slight bumps. The car seems to lurch sideways in the natural direction as I take the corner, then regain control millisecs later. I never experienced this in my old 2006 civic si and was wondering if it was the RTF or issues inherent to a sporty rear wheel beast like the 335is. It sounds more like the latter.

Your old civic does not have the same alignment and suspension setup as the BMW, nor does it give the same steering feedback, so of course it will not feel the same. This is not an RFT issue.

[Magik]

Your old civic does not have the same alignment and suspension setup as the BMW, nor does it give the same steering feedback, so of course it will not feel the same. This is not an RFT issue.

Thanks, that's all I wanted to clarify. This is my first high performance car and they are indeed a totally different beast.

[Stratman335]

The rft's do have a much stiffer sidewall and that's why we feel the loud "bam" when hitting a road imperfection. That's because the mag is taking the bulk of the force and it's not slightly rebounded by the tire.

I believe that may even be the reason why so many people think the stock mags are prone to cracking and stuff and have emailed BMW with complaints and law suits.
The mags are definetly not at fault. It's the roads that are garbage in most places that are at fault. Honestly there were times when my rft's were a godsend ( smooth highway areas) but unfortunately that isn't consistent with every area that I personally have to drive.

The bottom line is that there is no better between rft's and non rft's.
It comes down to which option each individual prefers much like how an older man may prefer a 745i over an m3 or Ferrari. Maybe the guy doesn't want a small tightly cramped cabin with loads of hp. He may possibly rather have a slower but more comfortable and luxurious ride.


At this moment in time I prefer my new set up but that may change drastically as I will end up at the track soon and really pushing my car around corners etc...

Make the choice on what you personally would prefer brah!

[Pyrogenic]

I have run flats right now and I live in an area with pretty crappy roads. So I usually get my alignment done ever 3 or 4 months. It seems that my tires only last 2 years and to replace them all is very expensive. My back two tires are almost bald again so I will be replacing soon but am now thinking of getting non run flats. But my trunk can't hold a spare...
I have a few questions - are the lifespans for run flats much lower than non run flats? is it the run flats that are causing my alignment problems? and do you think its possible to replace the part in my trunk to hold a spare?

[Silverpanzer]

Run Flats create a Evil , Noisy , shitty ride. Bad Idea

[Stratman335]

Run Flats create a Evil , Noisy , shitty ride. Bad Idea

That's correct but they're great when the roads are smooth