New aligment specs.. still feels vague

MoparLeo said

The guys who went through the most, were the engineers who designed the car. The farther away from stock specs that you get, the more guessing is involved. The most important component in the suspension is the tire/wheel combination. GO back to a more positive offset wheel and a smaller tire. The 215/70-14 tire is about the tallest tire available in a 14" and was last used on the Ford Ranger Pick-ups. A good size for an E-body but too large on a pre-70 A-body.

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There’s nothing wrong with running a 215/60/14, it’s not “too big”. I usually shoot for a 25.5” to 26” tall tire in the front, and a 215/70/14 fits that bill (~25.9”). Now those slots probably don’t have the right backspace, but that’s a different issue.

As for the factory specs, pretty much everything goes right out the window the moment you bolt on a set of radial tires. The factory alignment specs are wrong for radials, the factory ride height specs no longer give the best suspension geometry, the torsion bars aren’t stiff enough to deal with the additional suspension loads that are imparted by the radials having better traction, etc. The factory specs were ALL for bias ply’s, and the fact that the factory changed all that stuff with later models of cars designed for radials tells you the factory engineers would have done the same thing if they’d designed for radials instead.

It’s not “guessing” either. All of the changes can be predicted by looking at the suspension geometry and accounting for the performance of radial tires.