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[sokdo]

I was able to finally get my car up to 75-80 mph coming back down from work since I've gotten it couple of days ago and I don't know if its the run flats with the non sport wheels or what but the car feels very unstable or disconnected from the road when I'm going 80. It feels "floaty" when I'm at those speeds. I don't get that same feeling of being on the road as I did on my old TL. Would maybe changing the tires and bigger rims and maybe sway bars reduce this floaty feeling because although it's not that noticeable, it sorta makes me nervous to keep cruising at those speeds. Maybe its the run flats' sidewalls?

[persian54]

i feel very stable for speeds up to 110

havent really gone more than that in this car yet...

in my merc, i had Pilot Sports and PS2s, not run-flats, but they were fine u to speeds of 140 easy.

if you feel floaty that's not good...

tires old?

be careful... 75-80 isnt that much...

[sokdo]

It's brand new. Only has about 350 miles on it. This floaty feeling feels like the car isn't planted on the road. Like I'll be going straight on the freeway but the car will sway ever so slightly left or right occasionally ( maybe rocking is a better term? ) and I'm guessing harder/lower/sportier suspension would solve that but even for a stock car, it doesn't make me feel confident about driving it any faster.

[VTECaddict]

have your alignment checked, somethings not right. hell, even my accord felt solid over 80mph.

[sokdo]

Originally Posted by VTECaddict

have your alignment checked, somethings not right. hell, even my accord felt solid over 80mph.

I don't think it's my alignment. It's not like the car is pulling in a direction. The wheels are going straight, but the car itself which is ontop of the wheels feel floaty. =/ Not exactly sure how to explain it, prob have to experience it yourself to understand what I'm trying to say lol. I'm really hoping its the runflats because they have really large and solid sidewalls along with the stock suspension on regular non sport wheels which are I believe 17-16 inches?

[visor]

Check your tire pressures.

They may be too high if someone had forgotten to lower them to the proper setting during the PDI process. It is intentionally set high at the factory for transportation purposes so that the tires do not develop flat spots while sitting in the ship/lot/etc.

[sokdo]

Hmm alright thanks I'll try that. What is the ideal psi for these cars with runflats?

[vadim]

It may well be the alignment. I have RFTs and the car is planted to the road at any speeds. Have it checked.

Also, new tires need to be broken in. Give them ~500 miles; make sure they are properly inflated (I like mine being about 4-5 psi over the recommended numbers).

One more thing - it could be the steering feedback that you may not have had in your previous car.

[VTECaddict]

Check the door jamb. There should be a tire pressure sticker.

Alignment can affect more than pulling to the side. Caster and toe can have an affect on high speed stability.

[visor]

Originally Posted by sokdo

Hmm alright thanks I'll try that. What is the ideal psi for these cars with runflats?

The recommended values are pasted on the driver's door jamb, according to your tire sizes and widths.

Don't forget to check when the tires are cold, ie. not driven for a few hrs.

[sokdo]

X-x wow ok so many variables so it may either be:

1. alignment
2. too much tire pressure
3. not enough tire pressure
4. steering feedback
5. not broken in
6. cold tires

[VTECaddict]

You might also be experiencing tramlining (the car's tendency to follow grooves and ruts in the road). I find the OEM Potenza RFTs tramline pretty badly.

But if its a constant feeling of unstability, then its probably not tramlining.

Just take it to your dealer and go on a test drive with the SA to show what you mean. And see if they can fix it.

[visor]

Originally Posted by sokdo

X-x wow ok so many variables so it may either be:

1. alignment
2. too much tire pressure
3. not enough tire pressure
4. steering feedback
5. not broken in
6. cold tires

Heh! Welcome to the finicky world of BMW!

Anyways, the easiest is to check your tire pressures first.

I had exactly the same experience as yours when I picked up my new BMW a few yrs ago, floaty and all, and when I checked, the pressures were at 45psi!!!

[sokdo]

Originally Posted by VTECaddict

You might also be experiencing tramlining (the car's tendency to follow grooves and ruts in the road). I find the OEM Potenza RFTs tramline pretty badly.

But if its a constant feeling of unstability, then its probably not tramlining.

Just take it to your dealer and go on a test drive with the SA to show what you mean. And see if they can fix it.

I don't think my tires are Potenzas. It says Continental on the side wall. I'm also pretty sure it's not tramlining. I've experienced that before and it's not like that at all.

[visor]

Originally Posted by VTECaddict

You might also be experiencing tramlining (the car's tendency to follow grooves and ruts in the road). I find the OEM Potenza RFTs tramline pretty badly.

But if its a constant feeling of unstability, then its probably not tramlining.

Just take it to your dealer and go on a test drive with the SA to show what you mean. And see if they can fix it.

I believe the OP has 17 inch tires non sport, so doubt tramlining is the issue.

And if he takes it to the dealer, I would bet dollars to donuts that they will test drive it and will say that it is within normal limits!

[twinturboa51]

might be the car itself and downforce. i have the sport tires on my coupe and right around 70-80 it doesnt feel as solid as >80. it might have to do with the suspension tuning as well. the suspension i think is actually softer than the old 3 coupes to compensate for the rft harshness. as another poster said give the tires some time they may still have the mold release compound still on them. it takes a while for them to break in. but cant reaaly tell what youre experiencing without driving it. maybe go test drive another one and see if it feels the same.

[TurboFan]

Make sure the dealer pulled the blocks out of the springs. They put them there for shipping, I've seen where more than a few have forgotten to take them out.

[ibd12nv]

Originally Posted by Takashi

Check the road for windshear and cross winds. I notice that the E90 3 series are very suspectable to cross winds especially during highway driving at speeds of > 100 km/h. On windy days I feel that the car is not well planted on the road. On windless days (day or night) the car drives just fine.

Best answer thus far. I felt the same instability while driving in Germany at a over 120MPH with ZHP. It was the cross winds. They can be scary at 150 MPH.

[HighlandPete]

Originally Posted by sokdo

I was able to finally get my car up to 75-80 mph .....and I don't know if its the run flats with the non sport wheels or what but the car feels very unstable or disconnected from the road when I'm going 80. It feels "floaty" when I'm at those speeds.

Check tire pressures... but this 'floaty' feeling is common here in the UK on non sport suspension. I had it on my E91 touring (wagon) and the cause was the run-flat tyres. Sorted with Goodyear GS-D3 F1 tyres and even better now... on Falken 452.

BTW, BMW did a full KDS, but it's not alignment, that made no difference to the unplanted feeling.

HighlandPete

[visor]

So, sokdo, how were the tire pressures?

[sokdo]

How do I check it? lol I was fidgeting with all the control on my commute to work this morning and I couldn't find the darn thing. ( Don't worry, the commute is like 5 mph with stop and go so I wasn't endangering anybody ) I need to find the owners manual somewhere in the garage unless a nice person tells me how to find it

[visor]

Originally Posted by sokdo

How do I check it? lol I was fidgeting with all the control on my commute to work this morning and I couldn't find the darn thing. ( Don't worry, the commute is like 5 mph with stop and go so I wasn't endangering anybody ) I need to find the owners manual somewhere in the garage unless a nice person tells me how to find it

Uhhh...you can't check it from the driver's seat, if that's what you mean...

You'd have to get a tire pressure gauge:


and stick into into the tire valve stem like this:


If you've never done this before, you'll need someone to show you.