In rec.autos.tech, on Sun, 9 Jul 2017 13:03:26 +0000 (UTC), Chaya Eve
wrote:

On Sun, 9 Jul 2017 19:56:29 +1000, Xeno wrote:

The car steering geometry specs will have been designed to make your car
safe to drive in all circumstances.

The specs are almost always a *range* so there's room to be at one end or
the other, isn't there?

I think the answer is no, not always.

If caster has a range of 2 to 4 and camber 5 to 7, that doesn't mean
that you can put caster at 2 and camber at 7 and everything is even
moderately acceptable, aiui.

The range refers to one value at a time, that if the caster has a range
of 2 to 4 and you have it set at 1.9, that's bad in itself, regardless
of what the other values are. (Maybe in some special situations a
skilled aligner can safely go outside the range, I don't know one way or
the other, but my point is made in the paragraph above, which I think
you think would be acceptable.)

Alignment is a compromise and any particular setting of camber, for
example, may well limit the acceptable setting of caster to a smaller
range than the range given in the spec. Competent pros know this and
allow for it.

Corrections?

I hope you don't intend to tell the shop what settings you want, and
will instead tell them your problem** and what you think woudl help,
without ordering them to do that.

**I'm not sure why some feathering is worth all this trouble in the
first place. Will your tires wear out sooner? How much sooner? How
much is that in dollars?