I have played with http://www.1010tires.com
online (wheel and tire combos)
We can have better cornering and braking in dry conditions than the stock P205/70 r15 (wich are very good on bad roads because they absorb quite a bit of bad stuff or like i'm doing now for winter and deep snow ... it's almost here ... )
But in case you have good roads :
Maybe 17 inches with 215/55 R17 ... or you will see on the site ... your preference.
I have the irridium spark plugs - I suggest the NGKs, I saw a very big difference in smoothness ! and maybe a bit of miles/per gallon.
For the SE model with CVT we have to be patient and carefull to what we do to her ... she's a nice economical lady. with a good heart in heavy winter storms.
I love the Mopar hood protector - saves a lot paint shipping, + looks good with the Mopar rear wheel mud gards - looks a bit 4 x 4 that wants to bite the snow.