I'm looking into some beefier tires the next time around ( thinking of 245-40/17), but I'm not sure if wider is necessarily better. Has anyone tried wider tires on their stock rims, if so, were the results better? or is 215-45/17 the best the stock rims can get?

Also, has anyone tried the new hankook evos/what are your feelings on them?

 

Wider is not necessarily better. The biggest determinant of performance is the tire's design, including its compound, tread pattern, etc. So if you're looking for better performance, choose a stickier make and model of tire, rather than a wider tire. For example, stepping up to the Dunlop Direzza Sport Z1 Star Spec (or Bridgestone Potenza RE-11, Kumho Ecsta XS, or Yokohama Advan Neova AD08) in 215/45-17 will give you a huge increase in grip compared with the stock Michelin tires that came with the Si. Within this group, the Star Spec is also cost-effective, with a relatively low price and a current rebate offer.