The best thing I've ever done to any car is to revert it to its stock tyre size.
For the same money, better to buy high-quality tyres of renowned make and manufacture which are stock size rather than cheaper quality tyres which are wider.
It is better for status also. Example given: You see a civic with Michelin, Pirelli, Toyo or Continental tyres in stock size. OTOH you also see a civic (or charade for that matter) with General tyres many sizes wider than factory size. Which one would make a better impression?
Wider tyres do not give you better grip. Quality material does. For the same money you'd spend on widening, you could get stock size but a lot more durable, which would retain its grip and other properties for much longer.