BBS CH purchase- effects of offset change and going wider
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New Member
Joined: Jun 2008
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BBS CH purchase- effects of offset change and going wider
Hi All,
I am planning on getting new BBS CH's 18 x 8.5-The size available now.
The problem is the OEM BBS CH's on A4's were 18x8 with an offset of 43. The BBS CH's available now are 18x8.5 offset of 35mm.
The 35 offset puts the inside of the rim at same place as OEM, the outside of the rim at 1.5cm pushed out, and center line of wheel at about 7.5mm out.
This pushes the scrub angle out a bit and therefore should change the steering behavior slightly.
Question I have is for those of you who may have doen something similar--Going to a smaller offset or wider wheels--anything that moves the center line out and changes scrub angle/radius (or kingpin angle).
A) Is the 7.5-8mm significant or at all noticeable?
B) If there is a change, what is the effect on :
1) steering effort
2) Stability in straight line (slightly wider track)
3) Return to center force & Bump steer behavior
4) Other handling issues considering this is a Quattro system
Or is this just too small of a change?
Already talked to Tirerack about this but wanted to see if anyone has direct experience with changing offsets like this.
Thanks.
I am planning on getting new BBS CH's 18 x 8.5-The size available now.
The problem is the OEM BBS CH's on A4's were 18x8 with an offset of 43. The BBS CH's available now are 18x8.5 offset of 35mm.
The 35 offset puts the inside of the rim at same place as OEM, the outside of the rim at 1.5cm pushed out, and center line of wheel at about 7.5mm out.
This pushes the scrub angle out a bit and therefore should change the steering behavior slightly.
Question I have is for those of you who may have doen something similar--Going to a smaller offset or wider wheels--anything that moves the center line out and changes scrub angle/radius (or kingpin angle).
A) Is the 7.5-8mm significant or at all noticeable?
B) If there is a change, what is the effect on :
1) steering effort
2) Stability in straight line (slightly wider track)
3) Return to center force & Bump steer behavior
4) Other handling issues considering this is a Quattro system
Or is this just too small of a change?
Already talked to Tirerack about this but wanted to see if anyone has direct experience with changing offsets like this.
Thanks.
AudiWorld Super User
Joined: Oct 2001
Posts: 15,311
Likes: 696
From: SF Bay Area, CA
Can't answer you specifics, but as a big picture pointer...
often if you look from the baseline Audi model to the pumped up model, you will find similar width increases with less offset--in the C5 with the six cylinder model (in the mid 40's on offset and typically 7" type widths) vs. the 4.2 or the RS6 with the flares (35-30mm offset in 8" and 8.5" widths). Certainly in the recent A4 Vs RS4 (decidely less offset in a 9" width).
Personally I haven't noticed it as I have moved the offset around. Mostly just notice the grip as the width has gone up, with just a bit more steering effort at low speeds. And it clearly looks better as you get the wheels out toward the fenders in my opinion, as long as it doesn't rub and doesn't spray junk all over the side of the car if the fender lips aren't reasonably shaped for it.
Personally I haven't noticed it as I have moved the offset around. Mostly just notice the grip as the width has gone up, with just a bit more steering effort at low speeds. And it clearly looks better as you get the wheels out toward the fenders in my opinion, as long as it doesn't rub and doesn't spray junk all over the side of the car if the fender lips aren't reasonably shaped for it.
Tech Guru
Joined: Mar 2003
Posts: 6,006
Likes: 2
That's too small to worry about. more.
I am in general a stickler about offset, for all the reasons you point out. And many "experts" seem to think that "proper" offset means the wheel doesn't interfere with the suspension. Look at some of the so-called calculators out on the web.
That said, Audi goes -10mm all the time on its own cars, such as my S6. Or to place 16" snows on an S-car, such as the A62.7t or the b5s4.
I never noticed much on my S4. ( -45->-35). Maybe a bit more bump steer and steering tug. Maybe.
Don't sweat it. You're miles ahead even being cognoscente of the issues.
G
That said, Audi goes -10mm all the time on its own cars, such as my S6. Or to place 16" snows on an S-car, such as the A62.7t or the b5s4.
I never noticed much on my S4. ( -45->-35). Maybe a bit more bump steer and steering tug. Maybe.
Don't sweat it. You're miles ahead even being cognoscente of the issues.
G
AudiWorld Super User
Joined: Mar 2000
Posts: 3,617
Likes: 0
From: Utah, USA
Really too small to worry about. Pictures inside.
The difference is really so minimal. If anything, the ET35 CHs just look better and fill out the wheel well better. See below...
<img src="http://pictureposter.audiworld.com/158/audi_ch_2.jpg">
Audi CH - ET 43
<img src="http://pictureposter.audiworld.com/158/real_ch_2.jpg">
BBS CH - ET 35
So to answer your questions:
A) Is the 7.5-8mm significant or at all noticeable?
Not really noticeable.
Hopefully this is helpful.
John
<img src="http://pictureposter.audiworld.com/158/audi_ch_2.jpg">
Audi CH - ET 43
<img src="http://pictureposter.audiworld.com/158/real_ch_2.jpg">
BBS CH - ET 35
So to answer your questions:
A) Is the 7.5-8mm significant or at all noticeable?
Not really noticeable.
Hopefully this is helpful.
John
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