Over the years I have found that tracking that is even slightly out can have such an effect on tyre wear & handling that I never do it 'by eye' or with a piece of string, I take it straight down to the local garage which check it for free and if it needs adjusting, charge less than £20. Tracking that is only slightly out can scrub thousands of miles off a good set of tyres and cost more in the long run and that is ignoring the handling issue.
I drove it home from the garage last year after having the tracking adjusted following my fitting of some new solid steering bars (at £75 from Green Oval inc TRE's, VERY good value) at I was sure there was something wrong, I had it checked again and indeed they found it was a couple of points out, I could tell because it has always been an excelent handing vehicle but this time is felt slightly 'off'.
