Offset and "tramlining" and my imperfect memory

[Helge Wunderlich]

On Sun, 28 Aug 2005 07:40:02 -0400, Grant wrote:

>I'm generally a big advocate of maintaining offset regardless of wheel 
>width (my philosophy is that it the wider wheel dont fit without being 
>forced "out" from their steering center then they just plain dont fit). 

It makes sense. In general, if the car designers decided that
something is right, then it very likely is.

>  However, I see that you speak about "tramlining" -- or following road 
>slope toward the bottom.

In my case, it's actually opposite. The car wants to climb UP, out of
the ruts. If I let go of the steering wheel in the wrong moment, I'll
end up in the woods in a split second.

>This is typical of wide, low profile tires.  

Mine are 195/65, which is not radical, I think.

>It is also made worse by offset (positive - meaning the number, whcih 
>is in *minus* millimeters, goes down, as your example did).

I'm not sure I follow your sentence there, but I get the point.
Actually, I'd think that changing the offset *either* way could affect
handling negatively. The point is that the scrub radius must be as
close as possible to zero or slightly negative. Putting on rims with
too little offset causes the scrub radius to become positive, which is
bad. I found this nice picture: http://www.miata.net/garage/offset.htm

>ALl that said, I believe that Audi did supply 90q20v and coupe quattros 
>with 15 x 7 x 35mm speedlines.  I had one, and yes, it tramlined.

The question is whether the Quattro has the same suspension
configuration. It may be designed for a different offset, so it is
hard to compare. Do you remember what size tires you had?

>What 
>I also recall is that the 14" wheels they supplied had a 42-45mm 
>offset, as yours apparently does.

My conclusion seems to be going towards my rims simply being the wrong
ones for the car. The obvious solution is, of course, to replace the
rims, but that's a fairly expensive solution. Is there any other way
to fix the problem?

Thanks for your input, Grant.

Now I even know the English word for the problem. "Tramlining" gives a
lot of hits in Google.

-- 
Helge Wunderlich