Join Date: Mar 2007
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On the front, the king pin inclination or steering axis inclination (they are the same)really ought to be within 1/2 inch or the center of the tire tread. Putting offset wheels or spacers that move this alignment measurement lead to a number of problems.
The stress on the cartrige bearings is not a good thing, they will have almost no warning - good to go to no go in under 100 miles. If you have the older serviceable bearings - not a problem for reasonable tires.
Going to taller tires can move the alignment point out side the center of the tire so that some of the normal setting do not work well so that spacers or offset wheels will help with the head scratching at the alignment rack.
You can draw it on a piece of poster board, try to measure to 1/64 in from a straight edge on the hub flange to center of the ball joints. Sighting a straight edge held in line with the ball joints helps. Estimate the centerline of the hub to the line through the ball joints so you can measure it out on paper. Mark out the rolling radius of the tire and the KPI should be with in 1/2 inch of the tire center line, what it takes to get there is wheel offset or spacer. Old Tornados and centerline steer Intrenational trucks had over 4 in negative offset, Isee some custom wheels with over 4 in of positive offset and spacers start at 1/4 in.
One other thing to check is toe out or wheel cut angle it is not adjustable but showes bent parts that can cause the tires to rub when the wheels are aligned for the straigh ahead position. A bent spindle or steering arm can be adjusted so things look good until the wheels are turned then the bent parts change the angles.
93 Dodge /CTD, IC, 518, club cab LE, BHAF, KDP fixed, kelderman air ride
81 Isuzu /C223na, 5spd