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Last week I had an alignment at the Hummer dealership prior to getting new tires, because my front tires had worn heavily on the outside and required premature replacing.
The front camber wasn't off much (2.0/1.5 L/R) from the allowed "service check" numbers (0 to 1.75), but toe-in was (.64 degrees total). After the $300 alignment adjustments, the specs were 1.4/1.5 L/R and .21 total toe. I was surprised that the camber spec wasn't in the 0 to .5 degree range specified in the service manual (and in a Service Bulletin dated 3/96). I was told by the service foreman and mechanic that 1.5 is about as close as you can get to the 0 to 0.5 spec because they said you need to leave at least a thin shim or two in for mechanical reasons. I assume the reason for this is that AMG never planned for a lightly loaded hummer.
The mechanic said my outside edge tire wear was due to the out-of-spec toe-in number and not the camber settings.
I think it's also of interest to note that a second alignment check at the tire dealer, after the new tires were put, on showed a total toe-in of .92 (way, way out of spec) and camber of 1.7/1.45 L/R. So who's data do I believe? They both claim they're using the latest, expensive, laser based technology.
I know what your going through. Decent alignment is crucial for reasonable tire life, and a good ride.
Wear on the edges is due to incorrect toe. I've had problems with cupping on the rear tires also, which I believe was partially due to incorrect thrust angle.
Here's how I deal with tires and alignments:
Monitor the tread for wear patterns every other (or so) fill up. If any is noticed, or the vehicle doesn't track very well on the road, then I do a toe measurement. For this I break out a precision instrument....a tape measure. I simply take 2 measurements of the distance between the wheels on the same "axle". The difference will tell me if the tires are toe'd in or out. A slight toe in on the front and a slight toe out for the rear is desired. If not, and depending on the severity, then off to the shop. Keep in mind, this does not give you any indication of thrust angle. But paying attention to the tread and how she tracks will give you an idea of the thrust angle. FWIW- I've nailed the toe properties of the truck on all 3 visits to the shop. My first set of MTs ran for 52k, and the second set should last as long (fingers crossed).
Another tip- before beginning the alignment, have the ball joints and idler/pitman arms checked for play. A certain amount is acceptable, but an excessive amount will not keep the alignment. The shop manual describes how to do the checks.
good luck with it
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