The alignment itself won’t change before or after new tires, but, if the current front tires have uneven tread depths (between left and right tires) that can affect the steering wheel being straight. We always roadtest after the alignment, and the steering wheel may not be perfectly straight, due to uneven tread depth of the front tires. So we make a small adjustment to straighten it. If new tires are installed after that, then the steering wheel will be off center the other direction afterwards. Only takes a 1mm difference in tread between the left and right front tires to makes a noticeable difference.
This correct. Any thoroughly performed alignment is followed by roadtesting on an even road
and quite often there are some minor corrections required. What looks perfect on paper doesn't
neccessarily led to a happy customer who is looking at his steering wheel on every drive.
You'll guess it, here's my however: If the steering is apparently straight with the factory alignment
both front (and both rear) tires are likely worn the same and it's unlikely new tires will alter this.
Rear toe is equally important as front toe, not a tiny bit less.
I don't know how stupid this is but I've actually adjusted the tie rods to straighten the wheel quite a few times on various vehicles because I am kind of OCD about it. My understanding is that as long as you mark the rods and turn them the same amount (lengthen one and shorten the other), the alignment wouldn't really change. Sometimes I will turn them as little as like 1/32 of a turn and it makes a noticeable difference. I don't know how much you need to turn a tie rod to make a substantial change like say 0.2°.
Again, I agree. If you turn both sides the same front toe will remain the same and just the steering
wheel will move as long but only as long as you don't measure toe with the steering wheel center,
which of course is the way to do it.
You'll easily feel the slightest changes on toe. Just five minutes more or less will result in an difference
you'll notice immediately, much more (earlier) than you'd feel camber.
According to Google, one minute is .0167 degrees so you'd really have to move the rods a fair bit to affect the actual alignment a significant amount. That is good to know.
This is probably a good moment to remember that 1° is 60' (minutes). So one and a half degree
(of negative camber) is -1°30'. Or a total toe in of ten minutes is +0°10' (ideally +0°05' each wheel).
I don't like millimeters and inches as it varies with wheel diameter. Degrees and minutes are universal.
Lastly, I'd strongly recommend to keep the factory settings. Do you have the factory data on hand?
I'd bet it won't be
that different compared to a GTI or S3.
.