"Roll-Center", That is what the concept is called! Thanks for the link. I'm saving it for later.

 

As for the hub-centric-ness of the spacers I used, at least for the rear axle, they fit perfectly on the axle hub and the wheel fit perfectly on the spacer hub, both with hardly any wiggle. I was very pleased with that.

I have it easy in that very little salt is ever used on our roads. (Salt use on our roads is actually new to us in northern Idaho.) As such there was only slight surface rust on the rotors with nothing to interfere with the fit. I used the nuts that came with the kit to mount the spacers as the regular GM lug nuts would have been too tall.

With the 1.25" spacers, the lug studs and bolts were just a tad recessed into the spacer (1/8"?) and I was able to get 8.5 turns of the nut for good engagement with the stud.

 

I had no idea that i was so keen on tire placement until i put the 1.5's on the back and the 1.25's on the front.........I rounded a parking row at wall mart [that I have done many times before] and rolled right over the curb with the rear and also I cut into a parking space on an end with a curb [on the driver side and misjudged that one too.......... but I still like the set-up :-)

 

They do look pretty good but just remember, you are putting more stress on the rear axle bearings as you push the wheel & tire further out.
Although considering you are not running overly large tires; 30x9.5x15; you should be safe.
Just remember to check from time to time for excess wear.

Radar

 

Yes, I did not want to go too extreme; e.g. no spacers on the front, limiting the spacers to 1.25", not an extreme amount of suspension lift.