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[montreal_bimmer]

RFT suck man....

stiffer sidewall doesnt mean better handeling tire....

put those garbage RFT on a 335, and do some laps, then put Toyo T1R's on the same car do laps, and gaurenteed you will get better lap times with the Toyo's....

lighter, and wayyyyyyy better tread.

my opinion

[epiphone3]

Originally Posted by Richwm

Buy PS-II over stock RFT's

Pro's

1-Loose 12 Lbs of unsprung weight
2-Better gas mileage ( +2 mpg for me)
3-faster acceleration ( less unsprung weight)
4-higher cornering limits (.95 g's stock .98 with PS-II's)
5-better wet and dry traction
6-longer tire life
7-less replacement costs
8-better ride quality

Con's

1-no spare

So thats 8 to 1 any questions
read the compare at tirerack
http://www.tirerack.com/tires/Compar...speed_rating=Y

great post! I knew there would be a noticable difference in fuel economy, I didn't realise it would be as much as 2 mpg though! I thought maybe 1 mpg max!

[d3l0n]

Originally Posted by epiphone3

great post! I knew there would be a noticable difference in fuel economy, I didn't realise it would be as much as 2 mpg though! I thought maybe 1 mpg max!

+1

Great post. I saw the +1-2 difference for the past month. There is a flat tire kit for like no mroe than 90 bux on tirerack. The link is in one of my previous threads.. which i know have to search for.. when i get it ill post it here.

[epiphone3]

once I wear out my current RFTs, I will be making an effort to switch to non-RFT. Thanks for the info!

[bnj]

Originally Posted by epiphone3

To be honest, I don't know the exact weight difference... but I do know that it is significant and on the order of several pounds.

You should be aware that since it is weight located at the outer most area of each wheel, this extra weight will generate a lot of intertia (think of how fast the wheel rotates at, say, 60 mph). Losing rotating weight is one of the effective ways to improve your car's performance both in a straight line and in corners. In addition, the reduced weight will give the suspension a better ability to react to changes in the road surface hence improving handling, feel, and ride quality.

Guys, instead of giving these "facts" please search for the information. There is no significant difference in the 18" Potenzas. They are both 25lb. I guess I don't need to go to the theory of what is a significant difference...

[bnj]

Originally Posted by KevinC

What part? The entire thing.. especially the last line, which is just over-the-top ridiculous: Have another car if you want just a comfortable ride.

Look, you guys who like and defend runflat technology - more power to ya. But please don't tell the rest of us that these tires perform as well as non-runflats - because it just ain't true.

You can find it ridiculous that you can't have both comfort and handling in the same suspension/tyre setting. In my post, all the information is true or has a valid point. You are not able to find a single part in it which you could argue against for. Can you give me facts instead of just saying that RFT does not perform as well as non-runflats? Facts please!

[Lost Cosmonaut]

Originally Posted by montreal_bimmer

RFT suck man....

stiffer sidewall doesnt mean better handeling tire....

put those garbage RFT on a 335, and do some laps, then put Toyo T1R's on the same car do laps, and gaurenteed you will get better lap times with the Toyo's....

lighter, and wayyyyyyy better tread.

my opinion

+1 man.

I had like the first set of T1Rs in Washington on my STi and those things were GREAT. Excellent excellent tire.

Pilot Sport 2s are great too. I had Proxes 4s when they first came out and wasn't too impressed, at least not as a performance tire. And they felt weird in standing water too.

T1Rs are amazing, though.

- LC

[bnj]

Originally Posted by Richwm

Buy PS-II over stock RFT's

Pro's

1-Loose 12 Lbs of unsprung weight
2-Better gas mileage ( +2 mpg for me)
3-faster acceleration ( less unsprung weight)
4-higher cornering limits (.95 g's stock .98 with PS-II's)
5-better wet and dry traction
6-longer tire life
7-less replacement costs
8-better ride quality

Con's

1-no spare

So thats 8 to 1 any questions
read the compare at tirerack
http://www.tirerack.com/tires/Compar...speed_rating=Y

In the majority of the tire tests that have had both Potenza RE050A and Michelin PS-2 among the tires tested, Bridgestone has won. I say majority, since if the above is considered a full scale test, then we can say that in one test PS-2 has won

[agh!]

I'd like to pick up on bnj's assertion that RFT's are great...
On an E92 I beleive he is right, on an E90/E91 it is a different story.

I've been discussing RFT's with other E90/E91/E60/E61 owners for months and in short we hate them, many of us have switched to standard tyres with great results with only slight concerns over slight underdamping which we think can either be lived with, or corrected with Koni FSD dampers (to be tried). E60 owners go for Eibech springs and dampers though Koni FSD's are an option here too.
On my E91 I run slightly higher tire pressures and find that pretty much does the trick.
Two of the owners who hate RFT's on an E91 and E60 5 series have driven an E92 and are totally blown away by how it behaves. BMW have changed something with the E92 and it actually works perfectly on RFT's, you wouldn't beleive it runs on them, go figure!
On E90/E91 RFT's are rubbish, you only have to live with them for a year, or through a winter then change to standard tires (I have) to know this beyond doubt.

For punctures on standard tyres when you have no spare think "Ultraseal" as used by the US Marines.

[epiphone3]

Originally Posted by bnj

Guys, instead of giving these "facts" please search for the information. There is no significant difference in the 18" Potenzas. They are both 25lb. I guess I don't need to go to the theory of what is a significant difference...

what is your source for this "fact." I find it hard to believe that with all the reinforcement that goes into the side walls of run flats that they are not heavier. Plus, shipping always seems to cost more on RFTs as well... I guessing its not because they are lighter or more delicate

[jbake]

Reading one of my old BMW magazines, they report that the suspension was in fact "designed for runflats" they also stated that the RFT's perform MUCH better than a standard tire. They claimed that the runflat saved 10 SECONDS over a standard tire on the Nurburgring. The claim is more stable sidewall, faster turn in, less wasted motion. So all you RFT haters, I trust the engineers at BMW.

I can take a picture of the article and post it up if you don't believe me.

[bnj]

Originally Posted by epiphone3

what is your source for this "fact." I find it hard to believe that with all the reinforcement that goes into the side walls of run flats that they are not heavier. Plus, shipping always seems to cost more on RFTs as well... I guessing its not because they are lighter or more delicate

Source? E.g. Bridgestone catalog. Everywhere really. The Tire Rack etc.

[CnoteMD]

As far as the weight issue between RFT's and non-RFT's, I've checked the specs on TireRack.com and the difference is very small. In fact, comparing same brand and same size tires, the RFT's were almost identical in weight. Comparing other brands (I seem to recall Michelin PS2's being among the lightest), the Bridgestone Potenza RFT's were at most 2 lbs heavier.

There has been a lot of debate over the suspension being "tuned" for RFT's. To my knowledge, BMW attempted to give a good balance of handling and comfort while using RFT's (which do have stiffer sidewalls for obvious reasons). On the E60, BMW started using RFT's for the sport package equipped cars, and got a lot of complaints regarding the harsh ride (especially compared to the standard suspension cars that came with non-RFT's). Since all E90's are equipped with RFT's, they were able to design the suspension around a single type of tire.

Overall, the Potenza RFT's that come with the sport package are a very good tire. They handle fairly well and come in handy should you ever get a flat in one of those "wrong place, wrong time" situations (or even worse, 2 flats at the same time). Sure there will be a few compromises compared to some of the highest performing tires available. But then again, you would need to take your car to a track to really see those differences.

I would think that some of the body-kits, extra large wheels, and other mods so commonplace on this forum would be more of a detriment to performance than the RFT's.

[epiphone3]

Originally Posted by jbake

Reading one of my old BMW magazines, they report that the suspension was in fact "designed for runflats" they also stated that the RFT's perform MUCH better than a standard tire. They claimed that the runflat saved 10 SECONDS over a standard tire on the Nurburgring. The claim is more stable sidewall, faster turn in, less wasted motion. So all you RFT haters, I trust the engineers at BMW.

I can take a picture of the article and post it up if you don't believe me.

Yeah... a formula 1 car will lap the Nurburgring very fast but it will also be a punishing experience driving over bumps, etc.

Runflats ride hard... not only this, they wear poorly. I'd like to see BMW run laps of the Nurburgring with used RFTs and used non-RFTs. RFTs degrade pretty poorly in my experience so far. My Bridgestone summer RFTs cupped even though I maintained them at perfect pressure all the time and now they hum between 55 - 75km/hr all the time. Some tire design. Plus, they don't like seeing several successive bumps. By the way, when I am commuting in the city, I could care less about my car being 10 seconds faster around a 22km circuit.

Another question I have is why are all the people that have switched from RFTs on E90s to non-RFTs saying that they love non-RFTs better and that their car feels better than ever on the road? There has to be something to this.

[KevinC]

Originally Posted by epiphone3

Another question I have is why are all the people that have switched from RFTs on E90s to non-RFTs saying that they love non-RFTs better and that their car feels better than ever on the road? There has to be something to this.

ANYONE trying runflats and "real" tires back-to-back on an E90/92 would have the same impression. Hell, I was already grinning by the time I exited the parking lot of the tire store. I've yet to see anyone who's made the switch do anything but rave about the upgrade. OTOH there are plenty of people who never have experienced both who are steadfastly defending runflats. Ignorance is bliss I suppose. Too bad, they're missing out on turning their great car into a really great car.

[agh!]

I believe that on a good quality tarmac surface like the Nurburg ring the RFT's will out perform standard tires.
In real world road conditions, lumps, bumps, potholes, ruts in the road etc. RFT's throw the car off balance and tramline where standard tires soak up these imperfections and keep the rubber in contact with the road.
A UK magazine autoexpress did tests on Bridgestone's test track south of Rome, Italy and found RFT's to have a marginal lap time lead over standard tires. This is an irrelevant result to those of us that drive on real roads, especially in colder than Mediterranean temperatures.
There is also the fact that RFT performance degrades quite significantly as temperatures drop below the range for summer tires (much more so than standard tires) and as the tread wears down past the 5mm mark.

The experience on an E92 may be quite different from E90/E91 though.

[HighlandPete]

Originally Posted by KevinC

ANYONE trying runflats and "real" tires back-to-back on an E90/92 would have the same impression. Hell, I was already grinning by the time I exited the parking lot of the tire store. I've yet to see anyone who's made the switch do anything but rave about the upgrade. OTOH there are plenty of people who never have experienced both who are steadfastly defending runflats. Ignorance is bliss I suppose. Too bad, they're missing out on turning their great car into a really great car.

I'm one user who has two wheel sets and can make 'back to back' comparisons. Where do I start? "Chalk and cheese". I've had the RFT's back on the car and don't you know it.

I'm one of the guys who has tested the E92 on standard suspension and 18" RFT's, it's hard to be sure you are on a RFT shod car, so different.

I'm going to fit Koni FSD's on my E91, to try and find a better ride. Will report back soon.

HighlandPete

[HighlandPete]

The runflats are heavy and crash over bumps, and don't stay planted as well as a "real" performance tire. Leave your suspension alone and replace those crappy tires with PS2's and then try to tell me your car doesn't ride AND handle better with the new tires. Not only are both improved, but the difference is dramatic. Ask ANYONE who has done this and you'll get the same answer.

Exactly, the RFT's cause the car to dance about and you back off, as it is unnerving. I've got Goodyear F1's as my real rubber, 'planted' comes to mind here. No way do RFT's give the confidence to 'drive' the car. We are talkng BMW, so should we have to 'back off' because of a bad tyre/suspension mix?

Don't get me wrong, I've driven several E90/1's on different combinations and my favorite is the 3-litre M-sport cars. But only on excellent road surfaces. In my 'real world' sorry but "no way", I want a reasonably consistent drive, not a car where driving dynamics fall to pieces when the conditions are not perfect.

Highland Pete

[CnoteMD]

Originally Posted by KevinC

ANYONE trying runflats and "real" tires back-to-back on an E90/92 would have the same impression. Hell, I was already grinning by the time I exited the parking lot of the tire store. I've yet to see anyone who's made the switch do anything but rave about the upgrade. OTOH there are plenty of people who never have experienced both who are steadfastly defending runflats. Ignorance is bliss I suppose. Too bad, they're missing out on turning their great car into a really great car.

I have driven both and for normal driving, I would still keep my RFT's. I have driven almost identical cars back to back (RFT vs. nonRFT). I drive an E90 330i equipped with 18 inch Bridgestone Potenza RFT's. The same day I had the opportunity to take an E90 330i wearing aftermarket wheels and non-rft's (can't remember the exact model tire) for a couple of laps around Limerock Park (CT).

True, there is a difference in comfort. There is also a slight handling benefit to the non-RFT's. But unless you are doing completely ridiculous maneuvers on public roads, you would need a track to truly see the difference. From a convenience and safety standpoint, I'll stick with my stock tires.

Each person's driving conditions varies greatly. What I would have given to have had RFT's when I got 2 simultaneous flat tires after hitting a huge pothole in Brooklyn or the time my wife got a flat on the NJ turnpike.

[HighlandPete]

True, there is a difference in comfort. There is also a slight handling benefit to the non-RFT's. But unless you are doing completely ridiculous maneuvers on public roads, you would need a track to truly see the difference. From a convenience and safety standpoint, I'll stick with my stock tires.

I like the RFT concept, it just doesn't work in my driving environment. If the driving dynamics didn't fall apart, I'd stick with them. But a car that is literally 'shaking to pieces', is not the way I like to drive.

BMW used to make cars that drove well, with a decent ride quality, and you could still enjoy the sporty feel. But this RFT 'compromise' is not working in my opinion.

Highland Pete

[epiphone3]

interesting... I still continue to hear (almost) exclusively that in the real world of street driving, non-RFT is the way to go on an E90 and that there is not a huge difference on E92.

I think I will be making the effort to go non-RFT on my E90 here when the time comes for new rubber... I just pissed that my Potenza RFTs make the damn humming noise at certain speeds because my car is other wise quiet. Oh yeah, and successive bumps send shockwaves up my GF's spine.

[bnj]

Originally Posted by KevinC

ANYONE trying runflats and "real" tires back-to-back on an E90/92 would have the same impression. Hell, I was already grinning by the time I exited the parking lot of the tire store. I've yet to see anyone who's made the switch do anything but rave about the upgrade. OTOH there are plenty of people who never have experienced both who are steadfastly defending runflats. Ignorance is bliss I suppose. Too bad, they're missing out on turning their great car into a really great car.

That's the thing, you were already grinning by the time exiting the parking lot of the tire store.

You had an opinion already before driving. Of course, because you had made a choice already. You experience what you expect to experience. Moreover, new tires are better than old, and of course in a perfect balance.

I have been driving and tracking many Beemers with RFTs and non-RFTs. Same size RFTs are less comfortable, but appr. a second per kilometer quicker.

I am open to all choices when the time comes for the next set for my personal daily driver e92 335i. However, saying that Potenza RE050A RFTs suck is ignorance. Especially mated with e92 335i OE suspension they are fabulous performance wise. The thread is about Potenzas, not about Runflats in general.

Traditionally, European taste is towards performance & handling rather than comfort. It's understandable that I like my suspension (springs+shocks+tires) to be stiffer than you. I couldn't think of having my 335 without sport suspension or minimal flex in tirewalls. The turn-in must be sharp and I don't want my tires to wrap from the wheels in a fast curve, but be in a parallel with the ground offering the most grip. I have a tarmac rally suspension in my Integrale, and that has all the suspension elements a lot stiffer than my Bmw. Whatever funny theories people have here, the truth is that a fast tarmac suspension is very very stiff compared to any ordinary car suspension.

However, for your taste you can make a good choice having non-RFTs when its time to replace your old tires. But if you say my current tires are not good for me, I expect you even try to give me some facts. Because its quite bold of a statement. Especially, since I have been driving quite a lot of e92 335i at non-RFT's.