Maybe this is a stupid question, but is there any difference in how the car drives or handles in relation to the size of the rim?

Are there any negatives with having like 19" rims or is it just a visual upgrade, no more no less?

 

i don't know... I decided to go with 20" instead.

 

there is a huge difference with the larger rims.
#1 staggered fitment - will change the contact patch of the front against the rear introducing a different balance in under/oversteer (depends on suspension tuning)
#2 usually larger rims weigh more, introducing a gain in unsprung weight, slowing down the car, and putting a little more stress on the tranny (not enough to worry about). but the slowing down is easily overcome by a supercharger.
#3 but *the advantage* - larger rims usually means smaller sidewall tire (35 or 40 series), which equates to much better handling (usually putting on a z series), because of less roll, and a larger contact patch (again usually moving from the narrow 215 to a wider 245).
hope this helps.

 

also, because of the smaller sidewall, you are more 'in tune' with the road. and that does equate to a stiffer ride. which means you get more vibration and more road noise.