Am haveing a bit of trouble finding what i want from search. Between 14 in and 15 in rims what is the performance gains or loses between the two? I am looking to get the K rewinds 20 offset for a first gen

 

1. larger diameter = smaller tire sidewall
smaller tire sidewall typically means harsher ride and better response from the tires

2. larger wheel tends to mean heavier
heavier means
suspension doesn't do its job as good
car will be a bit slower due to inertia
etc

however, these rules are not universal...
-depending on the quality of wheel, a larger quality wheel could be lighter than a crappy smaller wheel
-likewise some tires are stiffer in general, so a tire with a larger sidewall could very well be stiffer than a tire with a small sidewall
-it depends on what wheels you get and what tires you get

3. lower offset than stock increases scrub radius, increasing necessary steering effort
not a big concern imo although some may argue otherwise