01-19-2013, 05:06 PM
Worlds Foremost Authority
Location: Upper East Side Manhattan - Lime Rock CT
Join Date: Jul 2007
Mein Auto: 2015 M4 Convertible
I bought an E93 335i with sport package in 2007. The car was purchased in South Florida and I had no issue with the suspension or the RFTs on the relatively pristine roads of South Florida. After a month and 2,000 miles I shipped the car to my home in NYC. The car was for all practical purposes undriveable on NYC roads. I kept the RFTs on the car for a few weeks and was so disgusted with the way it drove I was prepare to get rid of it regardless of how much money I lost. I joined a couple of BMW Internet forums and expressed my concerns. Several people suggested that I get rid of the Run Flats. Before I replaced them I took the car to Lime Rock Park (The Road Racing Center of The East) and drove it on the Autocross course and the skid pad. My friend Travis, who his a two time national champion rally driver and a Senior Skip Barber Instructor, also drove the car and pushed it very hard. I then replaced the RFTs with Pirelli P_Zero Nero M&S ultra high performance all season tires. The improvement in ride quality was dramatic and the handling improved as well. After the Pirellis had been on the car for a few weeks I took it back to Lime Rock and Travis and I repeated the test we had done with the RFTs on the car. We both felt that the car handled better with the Pirellis. The stiff sidewalls of the RFTs will provide "crisp turn in" which many people equate to good handling. The issues that I had with the RFTs was that they did not give a lot of warning before they loose traction and that they bounced all over the place on rough pavement and could stay in contact with the road surface.
Originally Posted by Malikbari
Need to share an BMW experience of runflat tyre ,bought a new BMW in 2006 m sport pack 318i saloon payed over £25000 when new it's been nearly 7 years now but never enjoyed a comfortable drive all this time worst was that I need to park the car for a year coz my wife was pregnant and could not afford to take a bumpy ride it was so terrible Try ringing BMW dealer can't change off market wheels it's not recommended from the manufacture and its your own responsibility if an accident happens ,very confusing dilama paid lot of money and now no resale value ,after all this terrible very terriable experience can anyone please suggest me some sort of solution for this problem ,I am not a complain machine but its a real exp and still in love with BMW
To generate maximum grip a tire needs a certain amount of what is called "Slip Angle". If you google "Slip Angle" you will get some good information. An overly stiff sidewall will not allow sufficient slip angle to generate maximum grip.
Even after I had replaced the RFTs I had an issue with the harshness of the suspension. I was getting "Pothole Explosions" and when I hit construction plates or other imperfection the car felt like it was going to break. Actually it did break. I had to replace 5 rims and 8 tires that were destroyed.
There was a lot about the car that I liked, the steering feel the way it handled (on smooth surfaces) and I was determined to try to get the suspension issues sorted out. What I eventually wound up with is a set of Conti DWS (non RFT) tires and a set of Koni FSD shocks. At this point the car is what I thought I was buying in 2007. The ride is firm, but not harsh or uncomfortable, the car handles better than it did with the OEM RFTs and dampers. Not having a spare tire or room for one is an issue. I have a Conti Comfort Kit, BMW Assist and a AAA Premium membership.
As for the safety issue I did not consider the 335i with RFTs and the stock suspension to be a particularly safe car. The car had a propensity to bend wheels and shred tires. I did not want my wife driving it by herself because I was afraid she would be stranded RFTs or not. I have been driving the 335i go-flat tires and no spare for 5 years and 40,000 miles. I had one flat tire that required me to call for a tow.
We eventually got 750Lix to drive in the city and use the E93 as a weekend fun car. The 7 has RFTs but they are not an issue. In comfort mode the car is oblivious to NYC potholes and in sport mode it handles the twisties amazingly well for a car of its size.
The car will actually handle better with go flat tires and will be an order of magnitude better with Koni FSD dampers. There will be no comparison in terms of ride quality.
Drivers Club at Lime Rock
The Glen Club (Watkins Glen International)
International Motor Racing Research Center
Cayman Club Nor'Easters
Madison Ave. Sports Car Driving and Chowder Society (Only a Vice President)
Sports Car Club of America
Polish Racing Drivers of America (PRDA)
American Mural Project
Simeone Foundation Automotive Museum
Mount Washington Observatory
Society of Automotive Historians
Last edited by captainaudio; 01-19-2013 at 05:07 PM.