Does your van still use the twin I-beam suspension? If it does, the only good thing about it is it is strong. It is REAL bad for tire wear because the tires are constantly tipping in and out on top as the van goes up and down over bumpy roads. Weak springs will raise the tires up and tilt them in on top. There are offset bushings to correct camber and caster but they only fix the numbers shown on the alignment computer when the van is stationary. They don't fix the increased arc the I-beams go through which causes a larger than normal camber change while driving.
The best you can do is to install a heavy duty shock absorber on the right front and a stiff strut rod bushing to reduce the tire wear. (You would typically put new parts on both sides but it is the right front tire that normally wears the worst).
By stabilizer bar, I'm assuming you're referring to the anti-sway bar, then yes, it will affect body roll on corners and not tire wear. If by chance you were referring to the strut rods that go from the I-beam to the frame, those bushings will let the I-beam move backwards if they are worn. That will cause tire wear mostly on the inner edges.
If Ford has switched to the upper and lower control arms, both camber and caster will be adjustable and the big advantage of that system is very little tire wear, but that only applies when the control arms are in the proper geometry. That all changes with weak springs. Here again, if camber is corrected when the ride height is incorrect, the final numbers on the printout might look great, but there will still be horrendous tire wear. The ride height should be checked first before doing an alignment.
Caster does not cause tire wear, at least not directly. Some vehicles, like Jeeps and Mercedes, call for real high caster settings which causes the tires to lean into a corner. Riding on the edges will cause rapid wear if you are accustomed to high-speed cornering in parking lots.
Caster will not change due to changes in ride height. What is most important is it must be the same on both sides to prevent a pull.
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Tuesday, December 7th, 2010 AT 2:55 AM