[Pynne]

Dear suspension gurus,

First of all, thanks for an excellent forum - being a new Bimmer-owner, your post and threads have already provided me with lots and lots of great information.

Moding is quite new to me, so please bare with me if my questions seems completely stupid and obvious.

Last week I got my new summer wheels, being 19" VMR (8.5/9.5) and replaced my winter setup (stock 16").
My car has stock non-sport suspension (EU-model if any difference to the US ones).

After changing to the larger wheel setup, my car feels quite floaty, handling seems "loose" and generally to much body roll for my liking (I thought the car handled like this before, but just seems even worse with the big wheels).

Is this comon when moving up in size?

I'm thinkning of changing the stock suspension to Bilstein B12 (Bilstein B8 dampers + Eibach Pro Kit) because of this - of course the drop would be a welcomed side effect, but the driving/handling is the main reason I am considering this. Don't want the car to be comfortablethough, as I drive around 20.000 miles a year.

Would this be the right way to go, and would this help me achive what I want (great handling while remaining comfortable)?

Appreciate the help!

[jon328i]

If you changed to non-Run flat tires with your 19's, it will give you a little floaty ride.

[Pynne]

My winters are non-rft, so don't think that is the issue.

[axis]

I've got Eibach pro-kit on the V1 BMW performance shocks and struts and the ride is very comfortable and controlled. It's also not much lower than the stock sports suspension at all. (I wish it was a little lower in the rear actually.)

[Pynne]

Originally Posted by axis

I've got Eibach pro-kit on the V1 BMW performance shocks and struts and the ride is very comfortable and controlled. It's also not much lower than the stock sports suspension at all. (I wish it was a little lower in the rear actually.)

How is this setup compared to the Bilstein B8 dampers?

[cvc 22349a]

Originally Posted by jon328i

If you changed to non-Run flat tires with your 19's, it will give you a little floaty ride.

+1 bushings and dampers become too soft when you switch to non-rft

[Pynne]

Okay, thanks - that would answer my first question :-)

So would the Bilstein B12 setup solve my problem - increasing handling, reducing body roll but keep a decent level of comfort?

[luckyu]

Originally Posted by Pynne

Okay, thanks - that would answer my first question :-)

So would the Bilstein B12 setup solve my problem - increasing handling, reducing body roll but keep a decent level of comfort?

I would guess that it's the mass of your new wheels that's causing most of the problem, because you have the non-sport suspension. And the B12 kit will likely reduce or eliminate the issue, because the B8 shocks will control the wheel movement more effectively. That kit will also reduce roll and weight transfer.

It would be good to measure the weight of your new wheel + tire, along with your old W+T previous weight, just to keep records for future debugging :-)

[will.c]

OP, whats your new offset? My guess on the floatiness, on top of all of the above reasons, is due to decreased offset, which may decrease the effective spring rate due to increase in suspension "moment arm" length, if you see what I mean..

[michaelalex17]

i garuntee what OP is talking about is the less stiff sidewalls of the non-runflats. i didnt read the thread but if he got non-runflats on his new setup, i can pretty much garuntee that is what he is feeling. the less thick tire sidewall causes this sensation.

[Pynne]

Originally Posted by wonho

OP, whats your new offset? My guess on the floatiness, on top of all of the above reasons, is due to decreased offset, which may decrease the effective spring rate due to increase in suspension "moment arm" length, if you see what I mean..

I actually dont know (as mentioned, Im really not a car techie), but one of my friends actually mentioned this as well, so will call the dealer and ask (just asked for 19" staggered setup of VB3 for an e90, and thats what my invoice says).

If this is the case, would the B12 do any good/solve it?

Appreciate the feedback!

[Pynne]

Originally Posted by michaelalex17

i garuntee what OP is talking about is the less stiff sidewalls of the non-runflats. i didnt read the thread but if he got non-runflats on his new setup, i can pretty much garuntee that is what he is feeling. the less thick tire sidewall causes this sensation.

Im riding Continental SportContact 5, so yes it is non-rft.

If this is the reason, would the B12 kit help?

[crypticc]

I felt that till I firmed things up again with suspension and roll bar mods. See my post

[jon328i]

Originally Posted by Pynne

Im riding Continental SportContact 5, so yes it is non-rft.

If this is the reason, would the B12 kit help?

i think the Bilsteins B12will help stiffen your suspension and help eliminate the floaty ride. I used Koni Yellows after switching my tires to non-rft's and it worked.

[Pynne]

Okay, so just got an answer from the place I bought the wheels, and they are an ET 40 front and ET 45 rear.

So Im running:
Front 8,5x19 ET 40 with 235/35/19
Rear 9,5x19 ET 45 with 265/30/19

Thinking about it, doesn't people usually run with lower offsets? And if so, what are the consequense of running to high offset?

[HighlandPete]

Originally Posted by luckyu

I would guess that it's the mass of your new wheels that's causing most of the problem, because you have the non-sport suspension.

This is my first thought, and it is unsprung weight at that.

Just be aware that a sportier setup will likely compromise the ride quality. A better damper is needed, but be careful of too big a change in spring rate, as that could lose your desired ride quality.

HighlandPete

[Pynne]

Okay, to sum up there is 3 theories:

1: Softer sidewall after changing to non-rft.
2: heavier wheels with larger tires/surface.
3: Wrong offset (can somebody confirm/decline this after I provided my specs above?)

Either way, what I am hearing is, that this is normal when doing the changes to the car I have done, and the B12 kit would most likely help improving handling and reducing body lean.

[jon328i]

Originally Posted by Pynne

Okay, to sum up there is 3 theories:

1: Softer sidewall after changing to non-rft.
2: heavier wheels with larger tires/surface.
3: Wrong offset (can somebody confirm/decline this after I provided my specs above?)

Either way, what I am hearing is, that this is normal when doing the changes to the car I have done, and the B12 kit would most likely help improving handling and reducing body lean.

I think your current 19's offset is within range, and i don't think this will be an issue. your non-rft tires (soft-sidewalls) is the one causing your floaty ride as i stated on my previous post.

[will.c]

Those offsets look alright. Do u have any spacers?

[Pynne]

Originally Posted by wonho

Those offsets look alright. Do u have any spacers?

No spacers atm., but Im thinking about changing suspension, so don't know if it would be required, even though the Eibachs shouldn't dropping that much?

[f30er]

Check your tire pressures too. I had the pressure on my tires a little too high and they felt floaty to me, lowering it just a few psi fixed the problem for me...

[Pynne]

Originally Posted by e92er

Check your tire pressures too. I had the pressure on my tires a little too high and they felt floaty to me, lowering it just a few psi fixed the problem for me...

Pressue should be fine, but thanks :-)