Just had work done this morning after new tyres and alignment and a resulting pull to the left resulting from an un-adjustable caster error.
Went to Pedders (at Geebung in Brisbane) with the report from the tyre mob. They look at the report but will not accept the results. A lot of alignments done by tyre places are less than ideal - mostly because of the quality or calibration of their alignment equipment. Pedders actually have top-shelf equipment and theirs is calibrated weekly! And these blokes really know their stuff.
Checked everything, fitted the appropriate caster correction kit and aligned things properly. Now drives dead straight.
I would strongly suggest that you spend the cash to have the experts do a check if you are having tramming problems, rather than simply playing with tyre pressures, etc. These thing will only mask the real problem.
BTW the job cost me considerably less that your original quote.