[HighlandPete]

Originally Posted by ///ajd

What I actually found was that the ride was still tolerable, and when I did ditch the RFTs I actually sort of missed them and the sharp handling they gave.

My introduction to RFTs was in the 5-series, 530d saloon and touring, and one of the first M-sport 535d tourings. I had read a little at the time, but never expected the poor showing that all the cars exhibited. The M-sport was to me, a rock hard disaster, the car itself was a superb example, 13k miles and ready to drive away. (All the kit we wanted, including HUD). I had got out of my 540i touring on M-Tech suspension, 17" wheels to try it. One totally composed and surefooted, the other a set of driving compromises, neither one thing or the other.

Now I know AutoCar had slated the ride/handling on the 530d SE they tested on 17" RFTs, clearly concerned where BMW had been, to sign off such a poor job, as it clearly didn't work on UK roads.

They commented on the crucial relationship with ride and handling (saying they are mutually dependent) the car failed to cope with intrusions and composure suffered, as the body was easily deflected off course. Then stated the old Five (E39) didn't suffer such problems. Sound familiar? It does to me, in 3-series cars as well, mainly due to the RFTs.

HighlandPete

[F31-340i]

Originally Posted by milesr3

There is an article on the new 1 Series M Coupe in the current Evo with an interview with the guys responsible for developing it. They claim that they didn't use runflats because it makes the steering response 'too wooden'.

No doubt true, though not sure what "wooden" means. M have never used runflats & Alpina also rubbish RFTs on their website.

May also be that the they made the 19"x10J (rear) wheels lightweight to reduce unsprung weight which meant they would also crack with RFTs....

What are those 13"s on, a Radical SR3? Have to admit 19"s wouldn't be a good idea on that...

[Em135eye]

Miles - now they are the sort of wheels that get me excited.

And these too...



And these:





Small, well made, bit of a "dish" to them.

Not 19s/20s/22s.

[HighlandPete]

My favourites... my old 540i. Staggered setup on the touring, unusual.



HighlandPete

[HighlandPete]

I do quite like my summer rims to be honest, but I think the 160's do look a bit bigger to the eye. Others have said that to me as well, asking are the wheels 18"?





HighlandPete

[F31-340i]

These are turbo fuchs....16" x 7 & 8 with contis.

I think 15"s 7x8 Fuchs look even better.

Can't complain about the handling, but the ride is worse than in my 330d on 19"s.

[ALF_E90]

It is pretty difficult to argue that larger wheels are anything other than a styling exercise - albeit one that does make a big difference to the looks. Journalists always make it very clear cars handle and ride better on the smaller standard wheel options, and various sports car manufacturers like TVR and Lotus made/make it clear they offer wheels bigger than 16" only because customers demand it.

My car-related area of "expertise" is Caterhams and they offer larger wheels- 14 and 15" - on the cars for styling reasons but everyone agrees for track use it has to be 13's. Even the weight differences between different tyre types of the same size make a remarkable difference to the drive.

I prefer the look of my car on 18's but the handling and ride improvements were too much to ignore, plus I'll get through two sets of rears and one of fronts a year - that's a lot of money for premium rubber and I don't want to compromise with non-premium stuff just to keep it looking nice. I spend up to 7 hours a day driving my car but very rarely look at it from the outside!!

It is a shame that people have come to associate a "sporty" drive with a boneshaker ride. Caterhams, Elises, and other cars I have driven a lot like Pumas are amazingly supple yet handle superbly. And I used to havea few Pugs like the 309GTI that got this very right. Modern car weights,and large wheels, are largely to blame - it is hard to make a heavy car handle well without being stiff.

[Muz]

Originally Posted by 335diesel

I must rush out and get some of these then....



Miles is right - big wheels weigh a LOT. I've checked the weights of many OEM BM wheels and almost all 19s (even Performance ones) weigh a hell of a lot. Even the most basic 17s weigh far less - about 25% less in many cases. Then add massive wide rubber and you have a wheel and tyre set weighing an awful lot more - add a set of light wheels to a bike and the difference is immense. Similar applies to a car.

Not only do these vast wheels weigh a lot, they are often extremely fragile, partly due to the design constraints but also the almost non existent protection from the elastic band profile tyres.

Again we live in the UK - which isn't a billiard board smooth racetrack. I'd hate to panic every time I saw a slight pothole or road imperfection. That to me is compromising the fun of driving and also slows you down - not really a performance enhancer.

I think I'm pushing it now. I fear imminent total exclusion again...

That's sort of what my 320D looks like, I went from 17" runflats to 19" non runflats with a 30 profile, the handling and ride are much improved.

The car now doesn't veer off wherever the hell it feels like it and bumps are less noticeable, I'm not saying they're gone all together, but I can actually drive with a Shell coffee in the cupholder without any real worry of it ending up all over the stereo.

And as for weight, I need to weigh the wheels, but the 19" BBS CH's feel lighter than the 17" Msports with runflats on, is this possible?

[Em135eye]

Pete - don't see many E91s on 160s. Great to see another one on here. Saw 160s on a Z4 last week and they looked spot on. Do you know our wheels are on the Wonder Wheels box?!

Muz - they are 20s on stupidly low profile rubber. Have you tried 17s with non RFTs?

[Muz]

I actually haven't, I went from the 17" RFTs to 19" non RFTs, I was expecting it to be worse in all honesty.

Is it the RFTs that cause the car to just go where it wants? is it a common thing?

[F31-340i]

Originally Posted by Muz

And as for weight, I need to weigh the wheels, but the 19" BBS CH's feel lighter than the 17" Msports with runflats on, is this possible?

It maybe possible e.g. if your BBS are forged - M Sports will be cast. Forging enables better material properties to be realised in the finished wheel, so less material can be used for a given strength, hence lighter.

When you say the handling is improved, how do you mean?

[Muz]

Oh right so they could be lighter.

As far as handling it just feels a lot more predictable, the runflats had a mind of their own.

[Em135eye]

Muz - my 17s on RFTs were a PITA. I'd just bought the car so I just thought "hey I can live with crashiness - it's a sporty car after all" but the tramlining did my nut in.

Non RFTS went on (well before all four were worn) and the tramlining just disappeared, wet grip improved immeasurably, dry grip improved a bit, the crashiness went. I cannot think of ONE bad point except that there is a danger of getting stranded. That's what breakdown cover is for!

Most wheels have become too two dimensional IMO - no "dishing" - just flat and fussy designs that have a magnetic attraction to kerbs. Must be getting old and harking back to the "good old days" again - 160s were about the nearest I could get to older style wheels (like the ones Pete had on his 540i - one of BMWs best ever wheels IMO) on a modern(ish) BMW.

[HighlandPete]

Originally Posted by 335diesel

Muz - my 17s on RFTs were a PITA. I'd just bought the car so I just thought "hey I can live with crashiness - it's a sporty car after all" but the tramlining did my nut in.

Non RFTS went on (well before all four were worn) and the tramlining just disappeared, wet grip improved immeasurably, dry grip improved a bit, the crashiness went. I cannot think of ONE bad point except that there is a danger of getting stranded. That's what breakdown cover is for!

My experience, one of my first written comments to my BMW dealer on the subject:

To be totally honest, having lived with the RFT’s for 6-months, I wish BMW hadn’t bothered. They spoil a good car. Bad when cold, constant ‘fidget’ on anything but a smooth surface, no straight line stability on some of our roads. The lack of stability almost feels as if you have a soft tyre. In fact my wife has got out the car to check, as she thought she had a flat. It is not like the ‘normal’ tram-lining, it is the strangest feeling, several times it has felt like ‘torque steer’ on a FWD high powered car. Very weird feeling. These sensations have been there from new.

Part of my general description of RFTs to my garage and BMW:

On good roads, in temperatures over 6-7°C the ride and drive/handling is just on the limit of acceptability, as the temperature rises it improves. Summer temperatures 18°C and above, it is even better, generally impeccable. There is a problem of crossing transverse ridges in the road. If you hit one in mid corner there is a definite unnerving ‘jump’ that normal rubber does not have.

Get onto ‘normal’ Highland roads and you have a fidgety ride, the steering starts losing the precision.

Lower ambient temperatures and it all goes to pieces. The car is shaking/vibrating on anything but the best surfaces. The steering is unpredictable and the ride unnerving. As an example of the steering feel, hold the wheel in mid position and you can feel the wheels pulling left and right under you. It’s tugging on the wheel. Try and drive a smooth line through a bend and gently feed the steering, it can ‘suddenly’ take a bite and pull you in quite dramatically. Correct it and it can equally ‘snatch a bite’ the other way.

Part of my my notes to BMW:

I've put my 'experimental' Goodyear F1 shod wheel set on the car this week, the transformation to the car is unbelievable. All the nonsense I've experienced is associated with RFT's, no doubt about it. I'm willing to have anyone drive my car with the original wheels and the experimental set and feel the different driving experience.

Besides the obvious DRAMATIC improvement to ride comfort, steering precision and a planted on the road feel, what really surprised me, is the total noise/fatigue levels have just evaporated. The constant vibrations through the car and from every bump and road imperfection, also felt through the steering wheel, are now so subdued, are at levels expected in 'real' BMW's. The intrusion and discomfort of an over worked suspension system, is so obvious now. How BMW ever passed this RFT system off as a fully designed package, beggars belief.

As you can tell, the RFT did nothing for ride or handling. Changing to a same sized (17") normal tyre gave me a 'real' BMW.

HighlandPete

[ALF_E90]

Originally Posted by Muz

And as for weight, I need to weigh the wheels, but the 19" BBS CH's feel lighter than the 17" Msports with runflats on, is this possible?

OEM wheels can be incredibly heavy and they vary a lot. One reason I'm going for style 185 17" is that, at around 10kg, they are 5kg a corner lighter than some of the 17 and 18" styles. 17's seem to vary from 10-15kg and 18's from 12-15+kg per corner (wheels only).

RFT weight a lot more than normal tyres. One thing I have never seen in tyre tests is weights published - I bet they vary a lot, and it is a factor in the handling and ride.

[HighlandPete]

Originally Posted by ALF_E90

OEM wheels can be incredibly heavy and they vary a lot. One reason I'm going for style 185 17" is that, at around 10kg, they are 5kg a corner lighter than some of the 17 and 18" styles. 17's seem to vary from 10-15kg and 18's from 12-15+kg per corner (wheels only).

RFT weight a lot more than normal tyres. One thing I have never seen in tyre tests is weights published - I bet they vary a lot, and it is a factor in the handling and ride.

I see your 185 pattern is listed @ 10.36kgs, the 160 @ 12kg, but it seems heavy, as the total weight fitted with the RFT was 23.2kgs, (weighed). The RFT is specified as 12.7kgs weight. I'll have to weigh a 160 with the winter on it, as I know the winter tyre is 9.7kgs, I weighed one before they were fitted.

Trying to compare tyre weights is difficult, as it is hard to find direct comparison spec's (load/speed), but seems an average of 3 - 5kgs different, for RFTs to non-RFTs.

HighlandPete

[F31-340i]

Just been down to the garage to weigh a 225M 19"x9J rear wheel with 265/30/19 non-funflat tyre = 24.7Kg. I don't remember the RFTs feeling alot heavier, but its along time ago now.

Thats 1.5kg / 6% heavier than the 17" combo you quote - I expected the difference to be more than that. If your non-RFTs are a full 3kg lighter (seems alot?) then the difference would be 4.5Kg / 22% heavier.

The fronts (only 8J wheel - 225 wide tyre) are probably lighter of course.

I'll weigh the winter 17"s when they're off the car.


EDIT

Just realised felgen katalog have started adding weights....

http://felgenkatalog.auto-treff.com/

....17" 160 style is 12Kg, 19" 225M style is 12.63Kg (this would make my 265/30 tyre non-RFT tyre 12.1Kg)

Style 193 and 194 (the 18" and 17" M Sport wheels) are relatively light at 11.2-11.9Kg, 10.4-10.7Kg respectively - lighter than 17" 160s

I would have though that the tyres would be lighter in the larger sizes - this would mean 18" M Sport MV3s with tyres would have less unsprung weight than the same car on 17" 160s? But this may not be the case if your winter 17"s are under 10Kg. Interesting.

[kaishang]

URL for wheel weights?

[kaishang]

Originally Posted by kaishang

URL for wheel weights?

is it on the BMW website or just the link above?

[F31-340i]

Originally Posted by kaishang

URL for wheel weights?

Its in my post, select model in pull down box "Baureihe:" on the left split screen, then click on a wheel design to see all the info. Some weights are missing. Does the link work?

Looks like the 18" 320Si wheels are pretty light (also fitted to Edition models a few years back).

[F31-340i]

Originally Posted by kaishang

is it on the BMW website or just the link above?

I'd be surprised if BMW released wheel weight info - and very surprised if it ended up on their website, which is almost universally useless for any technical information.

The felgen katalog could have mistakes, but someones put alot of effort in and the site has been going strong for years. It didn't have weights until recently I don't think (I only realised it did today).

[Em135eye]

Pete - interesting stuff!
Brilliant to have a proper, balanced discussion about the differences without any insults! Quite rare.
I'll get my wheels weighed when I can. 160s come up quite heavy for 17s but I suspect the non RFTs ate pretty light and the rims are extremely strong.