Massive caster variance Side to side

RustyRatRod said
Because the unlocked brakes allow the wheels to turn, which affects the caster measurement. If they are allowed to rotate, it's impossible to get a correct measurement. Not to mention, with the DIY caster gauges, what are you turning the front wheels with? The tire. With the brakes unlocked, you are severely affecting how caster is measured turning the tires using your hands. The proper way is to have the brakes locked and do the caster turn using the steering wheel, but that's about impossible to do using the DIY caster gauges. I guess you could do it with two people.

This still doesn't make sense.

I have these:

If you didn't see his video, here it is:

He used a gauge like this:

It is held against the hub. The wheel is not turned with the gauge attached, the wheel is tuned hard left and measured, then hard right and measured.
New tricks on an old dog.