Steve,
To some extent that is true, as even wheel size effects what geometry settings you should chose. However, you have to have a basic starting point, so you make the assumption that the car is straight not bent .

The figures may be made up, but they are made up by Boram RS technicians . They obviously work though, as is being advocated by other people that have set their cars up on this advice. You can diss it all you like, but I know how to make a Cossie go round corners. Obviously you cannot apply the same methods to different set-ups and I would never profess to know how to make your Escort handle .