Some replies to what you've been talking about here...
Thinner tires give a better grip. Thicker tires are better for performance, fuel consumption and ride comfort (less noise too). "thinner/thicker" refers to the ratio between the base width and side width (I don't know the English terminology). Every tire is a compromise, there's no perfect tire.
The rim size by itself doesn't mean anything except for aesthetics (it will mess up the speedometer tuning though). Lightweight rims will slightly decrease the car's unsupported weight, which has some small advantage I forgot. In road cars though, they're mainly for aesthetics reasons too.
What's more practical is the tires' air-pressure. Higher pressure (in the allowed scale!) gives better grip, performance and fuel consumption, while lower pressure gives better ride comfort.
Spoilers increase the tires' friction as speed grows, to slightly improve performance, fuel consumption and grip. However, they're only effective in high speeds. But they are also mainly an aesthetics thing (in America at least), just like those body kits that decrease the car's drag for the same purposes...
Anyway, as I said before, I think this stuff is silly... If you want a faster, better-gripping car, get a Miata with a big engine (or if you can, a Boxster or a BMW 3
). If you want a better-looking car, well, get a French car.
(see examples below
)
Peugeot: classic aesthetics.
Renault: wonderful creativity.
IMO, those simple, clean designs are much more aesthetic than all those mumbo-jumbo "sportive" mods, and creative body shapes are much more attractive.
OK, that's all.