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[S4to335]

My good friend stated that he was actually surprised at the handling of his 335i in the rain on the runflats. Can any of you guys in the rainy states comment? Coming from an all-wheeled drive Audi...I never even worry about this...just wonder how bad this is gonna be. The LSD would help here I am sure..maybe that quaife is in my future sooner rather than later????

[Russellnyc]

I haven't compared the 335i with runflats to the 335i with non-runflats directly, but I can tell you that I have no complaints about the performance of either 18" summer runflats or my 17" winter runflats. The ride quality in this car with runflats of either size is good in absolute terms.

[HyperM3]

FWIW my best friends wife has runflats on her Mini and after having to replace 2(run flats are VERY pricey to replace) they ordered a whole new set of tires and rims from Tirerack. Needless to say, the ride quality and handling improved so much that its like night and day in that car.

Ive been driving my other friends mini and I can tell you that in the rain these tires are such a hard compound that theres no traction. They slide all over and I dont feel comfortable driving it in inclement conditions.

The first thing Im going to do is swap out the run-flats with regular tires. Considering I have to turn the car in on lease with run-flats anyway, might as well keep them to put them back on the car when the replacement ones wear out. I dont know anyone with BMW runflats that hasnt had to replace a tire or tire and rim multiple times.

[s4iscool]

they are just fine, the tread is good for water channeling. Dont try to be Tiff in the wet and you will be fine.

[Robin_NL]

Handling is a different thing than grip(cornering) or traction(2wd vs rwd). My former 2 RFT equipped BMWs were nice and well balanced in the rain, and so is my Michelin Sport RFT-ed 335i.

Maybe the DSC/DTC interferes a bit earlier than normal but you shouldn't worry about a thing.

[homerunball]

I was cruising at 145 mph in the rain from Munich to Zurich last week. No problems whatsoever slowing down to 60 than going back up to 140, etc. mostly at high speeds where resistance to hydroplaning becomes more difficult.
I have drivien my share of high performance cars, used a plethora of tires and I am an engineer in the industry, personally I don't feel too much difference between runflats or regular tires in terms of noise, ride and comfort. This is subjective but its not a night and day difference like some people put it. I don't think it even deserves a discussion in the sense that it gets discussed on this forum over and over. I'm sure you can get hard scientific evidence of increasing vibration amplitudes with runflats but the differences are so small most people won't even notice the difference if they didn't know they had it. Unless you are tracking your car, run flats will be fine in any situation that a normal driver will ever face.

[homerunball]

Originally Posted by HyperM3

Ive been driving my other friends mini and I can tell you that in the rain these tires are such a hard compound that theres no traction. They slide all over and I dont feel comfortable driving it in inclement conditions.

You may be referring to summer vs. winter tires when talking about rubber compound. Hypothetically, if you took 2 tires of the same brand, model, season etc. (one being run flat and the other being regular) the outer rubber compound will be exactly the same. What you may be experiencing is what most people experience in the cold with summer tires. Run flats will not in any way be worse in the rain than any other tire. Rain performance comes from tread design, size, width and of course rubber compound.

With that said, I will also swap my runflats for the regulars, for cheaper replacement costs, lower weight and summer performance rubber compound.

[HyperM3]

Originally Posted by homerunball

Unless you are tracking your car, run flats will be fine in any situation that a normal driver will ever face.

Except when having to replace them at a cost of over $100 more each than regular tires. This affects me considering on a lease I will have to turn the car in with adequate runflats or put new ones on. Id rather buy regular performance tires than pay an extra 400+ for runflats.

[HyperM3]

Originally Posted by homerunball

You may be referring to summer vs. winter tires when talking about rubber compound on the tread.

I didnt mean compound, I meant sidewall hardness. My words came out incorrectly.

[Lassaxi]

Originally Posted by homerunball

I was cruising at 145 mph in the rain from Munich to Zurich last week. No problems whatsoever slowing down to 60 than going back up to 140, etc. mostly at high speeds where resistance to hydroplaning becomes more difficult.
I have drivien my share of high performance cars, used a plethora of tires and I am an engineer in the industry, personally I don't feel too much difference between runflats or regular tires in terms of noise, ride and comfort. This is subjective but its not a night and day difference like some people put it. I don't think it even deserves a discussion in the sense that it gets discussed on this forum over and over. I'm sure you can get hard scientific evidence of increasing vibration amplitudes with runflats but the differences are so small most people won't even notice the difference if they didn't know they had it. Unless you are tracking your car, run flats will be fine in any situation that a normal driver will ever face.

I would agree with you- I'm sure I have not driven as many performance cars as you have, but my general impressions are that (1) the difference between run-flats and non-run-flats in terms of handling and ride on the cars I have driven is minimal, (2) BMWs handle well, with or without run-flats, and (3) BMWs eat tires, run-flat or not. I am sure that, as with any tire, there are quality differences between different brands and models of run-flats, and perhaps the Bridgestones that many of the 3ers wear are not the best quality, but I don't think the situation is nearly as bad as some people describe it.

[HyperM3]

OK, I think this might have gone off the track. In terms of handling, the run-flats are just as good as regular tires. What the bigest difference to me in my experience with them is ride QUALITY. The run-flats produce a much more harsh, bouncy ride than regular tires. I think that the hard sidewalls make the tires pitch more over bumps and dont settle as well. Thats what I was trying to say originally.

[bnj]

Originally Posted by HyperM3

OK, I think this might have gone off the track. In terms of handling, the run-flats are just as good as regular tires. What the bigest difference to me in my experience with them is ride QUALITY. The run-flats produce a much more harsh, bouncy ride than regular tires. I think that the hard sidewalls make the tires pitch more over bumps and dont settle as well. Thats what I was trying to say originally.

This is true. If you change to non run-flats the ride becomes softer and more comfortable. In order to compensate and achive the original planned stiffness to the suspension system, you should change also for the stiffer springs/shocks. When the total stiffness of the system is the same as original, you have basically the original level of handling/harshness and the car behaves similarly as planned by BMW.

[HyperM3]

Originally Posted by bnj

In order to compensate and achi(e)ve the original planned stiffness to the suspension system, you should change also for the stiffer springs/shocks.

I honestly dont believe BMW designs their suspensions around the runflats. That would be silly considering most people will change their tires and wheels anyway. What the suspension IS built upon is the size of the tires front and rear and its then calibrated that way. When people +1 or more thats when the handling characteristics start changing.

[bnj]

Originally Posted by HyperM3

I honestly dont believe BMW designs their suspensions around the runflats.

BMW claims to design their suspensions to be mated with runflats.

[HyperM3]

Originally Posted by bnj

BMW claims to design their suspensions to be mated with runflats.

If thats so, please cite your source.

[SE3P_to_E90]

Old thread... anyway,
i just switched from 235 and 265 Goodyear GSD3 F1's (summer performance) to 225 and 255 Bridgestone RFT...

IMO, the RFT sucks. During spirited driving, the car tends to oversteer tremendously compared to that of the GY F1's... albeit they were a bit wider, they held on to the road (IMO) nearly 2x as well.

[lhN54heaven]

Originally Posted by HyperM3

FWIW my best friends wife has runflats on her Mini and after having to replace 2(run flats are VERY pricey to replace) they ordered a whole new set of tires and rims from Tirerack. Needless to say, the ride quality and handling improved so much that its like night and day in that car.

Ive been driving my other friends mini and I can tell you that in the rain these tires are such a hard compound that theres no traction. They slide all over and I dont feel comfortable driving it in inclement conditions.

The first thing Im going to do is swap out the run-flats with regular tires. Considering I have to turn the car in on lease with run-flats anyway, might as well keep them to put them back on the car when the replacement ones wear out. I dont know anyone with BMW runflats that hasnt had to replace a tire or tire and rim multiple times.

I couldn't agree more...I've got Michelen Pilot Sports on a set of Beyren Mesh wheels. Dramatic improvement under all driving conditions. Taking away the full sized spare and making these heavy, noisy, gripless pieces of sh-- run flats standard on their 3 series is almost unforgiveable...how could BMW be so stupid...they get so much right with their cars...run flats and not equipping the 335i e90 "non-sports" package models with an external air/oil cooler are my biggest concerns everything else, so far, is heaven...man do they make a bada-- engine.