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[sycd]

Hey guys, I was frustrated like many by the RF tires which came from the factory on my 2008 335i E90 sport package. I even had to replace one of them after hitting a bad pothole a while back.

So when it was time to get my 3rd set of tires (car has about 60k miles), I decided to switch to non-run flats. Since winters can get pretty cold where I live, I picked a set of all season Continental DWS.

After 1k with these tires I'm ready to move back with the RF Michelin. I have a couple of major problems with these new tires:

- the car feels a bit softer, however it's lost some of its handling "edge". It doesn't feel as planted and confident as it did with the RFs. I'm sure this is due to the softer sidewall.

- under heavy acceleration, the car feels like it is not stable and shakes a bit. This stops right away when I stop pushing it, so it's not a balancing issue. It started right away after the install so I'm pretty sure it's not an engine or drivetrain problem. I'm currently stock and planning to buy a JB4 soon, so this is an issue.

So while the ride is a little softer, which I don't care for, and I don't have to worry as much about potholes, I'm really disappointed by the performance and feel of the car after making that switch. I feel like I'm not tapping into the entire performance of the car, and want to go back to run flats.

These new tires might be ok with the non-sport or non-turbo cars, maybe it would have been better to stick to summer tires, maybe I'm going insane. Anyone with a 335i sport package had the same experience?

[Gravy]

Hell yea. I thought it was my imagination... I noticed the handling difference right away... It rolls more during slight changes in direction... Traction is better though. The vibration is hit and miss with me. You will get used to it soon like i did hopefully.. Also, i still have the potenzas on the fronts btw. Im sure it makes a bit of difference

[nkadisha]

Not the same experience at all, the minute I had them changed I couldn't believe BMW would even use run flats. Maybe it's the type of tire thats causing the problem?

[jwalker87]

Probably because you went with all-season tires! If you got Michelin PS2's or something like that, I'm sure the performance would eclipse the run-flats.

[bigj505]

i replaced my RFTs with Nitto INVOs and have been very happy.

[captainaudio]

The "crisp turn in" of the RFTs is due to the overly stiff side wall and is more of an illusion of impoved handling than an actual improvement in handling. A tire needs a certain amount of slip angle to generate maximum grip. Too little slip angle due to an overly stiff sidewall will be detrimental to handling and although the car may feel like it is has a crisper turn in it will generate less grip than a tire with a bit more sidewall flex. This is one of the reasons that the M3 does not have RFTs and the racing version of the M3 does not run 19s.


This has been discussed here before but this is a good explanation

Slip Angle

Return to the tracking page

Slip angle is the angular difference between the direction the tyre contact patch with the road is pointing and the direction of the wheel (figure 1, below). This sounds odd - you might expect that the tyre tread would point in the same direction as the wheel wouldn't you? It doesn't because being made of rubber, the tyre sidewalls deform, and the tread pattern itself can 'squirm' when the wheel is turned from the straight-ahead.
In fact, modest slip angles are 'good' as tyres generate progressively more grip with increasing slip angles (figure 2, opposite), albeit up to definable limit where after no further grip is generated. Thereafter, increasing slip angles are 'bad', and the tyre will tend to loose grip.
Therefore, it should be apparent that if the slip angles for the front and rear tyres are the same (the tyres front and rear are generating similar levels of grip), the car will steer essentially as if there was no slip angle at all (neutral cornering).

Figure 1. Definition of slip angle. Note how the contact patch of the tyre need not be in the same orientation as the whole wheel, often lagging a few degrees behind.

Now let us consider what happens when the slip angles exceed our optimal grip generation limits. If the rear slip angle is larger than the front one you have a condition known as over-steer while if the front slip angle is larger, the condition known as under-steer results (also see the explanation on the tracking page). You will recall that a slip angle results from a combination of tyre sidewall flex and tyre traction. Note that if there is no traction (on ice, for example), then the slip angle will become essentially zero. On the other hand, if a wheel travels in a direction other than the one its contact patch is pointing, then you have a SLIDE angle rather than a slip angle.
Slide angles and slip angles are VERY DIFFERENT. Inertia determines the direction the car will travel if it slides (centripetal force). If you lose traction you will slide in the direction you were travelling at the time the slide starts. So long as you have traction you will travel in the direction the contact patch points, not the tyre. Slide angle is the angular difference between the direction inertia sends you and the direction your tyres are pointing while slip angle is the angular difference between the direction your contact patch is pointed (thus, the direction the tyre moves) and the direction the tyre is pointed.
Decreased traction reduces slip angles and increases slide angles!
Figure 2. Lateral force versus slip angle. Note that lateral force progressively increases from 0 degrees slip to a peak at about 8 degrees. Thereafter, the adhesion is lost, and the lateral force that the tyre is capable of generation progressively deteriorates.
What else affects slip angles? Acceleration and braking, tyre profile size and tyre camber. Acceleration and braking affect traction primarily because of weight transfer and toe-angle changes.
The greater camber, the greater the camber thrust. Camber thrust attempts to turn your wheel into a turn in the direction of lean. Thus, greater camber thrust yields smaller slip angles.
Given that the rear camber of the MGF is greater than the front, you should expect that the rear tyres are almost always operating with a lower slip angle than the front tyres. (I.e., your car tends to under-steer.)
What changes a slip angle into a slide angle? Excessive slip angles!!! That is, a slip angle is so called because the part of the contact patch that is to the outside of your turn is moving faster than the wheel itself is in the direction it (the contact patch) is pointing while the part on the inside is moving more slowly. (Exactly like camber thrust.) Since the outside part is moving faster than the tyre it must be slipping. The inside part is gripping better than it would if moving in a straight line. For this reason the contact patch 'walks' itself into the turn.
The greater the slip angle, the larger portion of the contact patch that is slipping. At some point there is so little part of the contact patch that is not slipping that traction is lost and the tyre begins to slide. Until shortly before then, slide traction increases. Note, however, that traction is generally not lost all at once. Rather than an abrupt loss of traction, it tends to be lost gradually. (Thankfully!!!)

[PKL]

tire purchase fail. try some better tires! RFTs are the WORST!

[tibra1]

^Great technical answer..OP just get some non-rfts w stiffer sidewall.

[j2m]

Originally Posted by PKL

tire purchase fail. try some better tires! RFTs are the WORST!

Yeah I would have to agree, maybe just the all seasons. i just switched from RF's. I ran RF's on my 08 and when I bought my 2011 I decided to switch to non-RF's. I went with Pirelli Rosso's and the improvement in HUGE. Besides traction I have noticed that the car is much more "planted" and does not skip when cornering anymore. I do not have any vibration at low or high speeds, and I have run them pretty hard. Maybe try a different tire like the Michelin Super Sport, they have had great reviews.

[Tom K.]

While I have them on a NA6 (128i), I found that increasing the pressures by about 3 psi all around pretty much tames the somewhat mushy turn in feel.

Tom

[captainaudio]

Originally Posted by j2m

Yeah I would have to agree, maybe just the all seasons. i just switched from RF's. I ran RF's on my 08 and when I bought my 2011 I decided to switch to non-RF's. I went with Pirelli Rosso's and the improvement in HUGE. Besides traction I have noticed that the car is much more "planted" and does not skip when cornering anymore. I do not have any vibration at low or high speeds, and I have run them pretty hard. Maybe try a different tire like the Michelin Super Sport, they have had great reviews.

The skipping while cornering is the worst aspect of the handlng of the RFTs.

CA

[taibanl]

If it's feel you are going for...add 3psi.

[Dark_Knight_335]

Wow, first thread I've seen where people want to go BACK to RFTs. I had a fleeting moment where I missed them, then I remembered all the bone jarring shockwaves going over the slightest road imperfections and I'm good again lol. LOVE my Yokohama S drives

[Blue Streak]

I went through 3 sets of Yoko S-Drive's and liked them... Now I have Conti DWS and they were way too soft, but after adding 3-5psi all around, I like them better than the S-Drive. So give that a try.

[RaceBlood]

Well softer is better than harsh, but why all seasons? Conti Contacts 2's is the way to go...

Get summer performance tires, then get a winter set. RFT is like having a brick for a tire.

I like the Hankooks too, super smooth, good on the track too...

[B-737]

Originally Posted by SDeFranco1

Wow, first thread I've seen where people want to go BACK to RFTs. I had a fleeting moment where I missed them, then I remembered all the bone jarring shockwaves going over the slightest road imperfections and I'm good again lol. LOVE my Yokohama S drives

lol!
Sal are those all seasons?

u guys okay up there i?

[Gator328i]

I guess I'm in the minority along with OP, but I have gotten used to my RFs and really don't mind them anymore. I have heard several stories similar to OPs where people have switched from RFs to Non-RFs and the car's handling characteristics become worse. Obviously, if the car's suspension is tuned for RFs then it's only going to perform the way the engineer's intended with RFs on it.

They seem to be improving each generation of RFs so I'm not concerned with sticking with the RFs. It's interesting that while M3s don't come equipped with RFs, many Ferraris do.

[pruettfan]

Going from a summer tire which is what your car had on it to an all season is a serious downgrade in performance. I dumped my RFT's and went to Michelin PS2's which are excellent. I lost a tiny bit on turn in quickness but I gained so much more in all other areas I would never go back.

[captainaudio]

I replaced the OEM Potenza RFTs with Pirelli P_Zero Nero A&S all seasons. They are far superior to the Brigestones in every respect and I wanted all seasons because it is not practical for me to have a set of dedicated winter tires, I never take the car out in the snow so dedicated snows serve no purpose but I do take it out when the temperature is below 40 degrees.

I took the car on the Lime Rock autocross course with the RFTs and then a week later with the Pirellis, I drove and a friend who is a Skip Barber insructor and a 2 time national autocross champion drove, We both concluded that the RFTs sucked,

CA

[captainaudio]

Originally Posted by Gator328i

I guess I'm in the minority along with OP, but I have gotten used to my RFs and really don't mind them anymore. I have heard several stories similar to OPs where people have switched from RFs to Non-RFs and the car's handling characteristics become worse. Obviously, if the car's suspension is tuned for RFs then it's only going to perform the way the engineer's intended with RFs on it.

They seem to be improving each generation of RFs so I'm not concerned with sticking with the RFs. It's interesting that while M3s don't come equipped with RFs, many Ferraris do.

If there is one thing that has become blatantly obvious to me it is the fact that the engineering team that designed the 3 Series sport suspension were clueless.

Driving in Florida and driving in the Northeast is like being in two different planets, If I had kept my car in Palm Beach, where I purchased it, I would have no issue with the RFTs. Once I shipped the car to Manhattan the RFTs were gone in two weeks and the OEM dampers were eventually replaced with Koni FSDs. In stock condition the car was for all practical puposes undriveable in the NYC area,

CA

[plokij]

you should have read a review first.

conti dws get seriously dinged for being too soft. most sports car owners claim they feel unstable / unsafe.

if you want a/s performance tires i don't think there is a better match for a 3er than michelin pilot sport a/s plus.

[x26]

Originally Posted by sycd

Hey guys, I was frustrated like many by the RF tires which came from the factory on my 2008 335i E90 sport package. I even had to replace one of them after hitting a bad pothole a while back.

So when it was time to get my 3rd set of tires (car has about 60k miles), I decided to switch to non-run flats. Since winters can get pretty cold where I live, I picked a set of all season Continental DWS.

After 1k with these tires I'm ready to move back with the RF Michelin. I have a couple of major problems with these new tires:

- the car feels a bit softer, however it's lost some of its handling "edge". It doesn't feel as planted and confident as it did with the RFs. I'm sure this is due to the softer sidewall.

- under heavy acceleration, the car feels like it is not stable and shakes a bit. This stops right away when I stop pushing it, so it's not a balancing issue. It started right away after the install so I'm pretty sure it's not an engine or drivetrain problem. I'm currently stock and planning to buy a JB4 soon, so this is an issue.

So while the ride is a little softer, which I don't care for, and I don't have to worry as much about potholes, I'm really disappointed by the performance and feel of the car after making that switch. I feel like I'm not tapping into the entire performance of the car, and want to go back to run flats.

These new tires might be ok with the non-sport or non-turbo cars, maybe it would have been better to stick to summer tires, maybe I'm going insane. Anyone with a 335i sport package had the same experience?

Yep. Absolutely!!

I lved my orm bridgestone RFT's--Car took turns/corners like it was on a Rail.

Got the Michelin A/S plus and althiugh they ride great and are sticky they give alot more on cornering.

My Summer set up is going to be RFT's!!