Wheel offset question

[Chris Thorp]

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