Wheel offset question

[Grant Lenahan]

If people want an explanation of scrub radius, I'll give it yet again.

I generally get ignored "cuz it looks so bitchin"

Grant
On Nov 2, 2006, at 6:01 PM, Taka Mizutani wrote:

> Let me just make sure I understand you- you have 0.25" clearance for 
> your
> brakes having test fitted the wheels you are buying?
>
> If that is correct, then you are FINE. :-)
>
> The 15mm offset difference will not be too much to worry about. It will
> affect
> your scrub radius (I don't understand this, but I'm sure someone can
> explain).
> Other than that, no big deal.
>
> Two things to check, though- much heavier wheels will affect your ride
> quality
> significantly; and your alignment is the most important factor in 
> proper
> tire wear.
>
> ET30 would be pretty common for front wheels for big MBZs- S-Class and 
> the
> like.
> ET32 is the OEM offset for a bunch of MBZ wheels, I'd make sure that 
> you
> don't
> have a staggered set (rear ET13 won't fit w/o modification and 
> staggered
> wheels
> are really not right for an Audi in terms of handling and the look).
>
> Taka
>
>
> On 11/2/06, Chris Thorp <thorp at spacia.org> wrote:
>>
>> I was buying used wheels.  I did a test fit before buying and that's
>> where I got the 1/4" number from.  I did realize that offset and
>> spoke design are two different contributing factors to brake
>> clearance.  The stock ET45's clear by about 1/2", but only because
>> the spokes are really cupped in exactly the right way to clear the
>> brakes.  (Go figure for stock wheels...)  The new ones are a bit
>> flatter but also less offset, which cancel each other out.  The
>> wheels were supposedly from an Audi, then run on a Passat.  They look
>> like (and probably are) the Borbet CF wheels, as shown on the Borbet
>> website.  What normally runs an ET30?  Maybe an MB?  (They're in 
>> 5x112)
>>
>> Since they were $100 for the set, in reasonable shape, I figured I
>> couldn't go too wrong.  I was just wondering how much an effect 15mm
>> less offset would have on handling as well as suspension and tire 
>> wear.
>>
>> -Chris
>>
>> On Nov 2, 2006, at 3:39 PM, Taka Mizutani wrote:
>>
>>> Chris-
>>> I know this isn't well documented, but I cannot stress enough that
>>> you cannot
>>> determine wheel clearances by the offset.
>>>
>>> This is a mistake that is done over and over again on cars with big
>>> brakes- I see it
>>> all the time on NASIOC, quite a bit elsewhere as well.
>>>
>>> Wheel clearances are determined much more by the spoke clearance,
>>> which is totally
>>> dependent on the wheel design.
>>>
>>> I ran ET45 S4tt Avus on my car with bulky 996 calipers w/o any
>>> clearance issues. I've
>>> also run ET35 Oettinger wheels and ET30 AZEV wheels w/o any
>>> clearance issues.
>>>
>>> If you're not sure if it will fit, you MUST test-fit before buying
>>> or find someone who has
>>> the wheels you're interested in and can verify fitment.
>>>
>>> If you're running the stock brakes, checking to see if a major
>>> vendor (like Tire Rack) sells
>>> the wheels you're interested in and sells them in a fitment for the
>>> A6 2.7T would be a good
>>> move.
>>>
>>> What wheels are you considering? ET30 is a bit unusual for an Audi
>>> wheel.
>>>
>>> Taka
>>>
>>>
>>> On 11/2/06, Chris Thorp <thorp at spacia.org> wrote: Yah, I know,
>>> wheel offset has been beaten to death.  I searched the
>>> archives and couldn't find anything conclusive.  Should I expect any
>>> major issues going from a factory ET45 wheel to an aftermarket ET30
>>> wheel on a '00 A6 2.7t?  Also, how little clearance is too little?
>>> I've got about a 1/4" or so between the spokes and the calipers.
>>>
>>> -Chris
>>
>>
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