Someone posted a video of a Sportage with 22" rims, I think from somewhere in the Caribbean? I have some lightweight 20's for the summer (TSW Interlagos wtih Hankook V12 rubber)...if only there was a big brake kit available.
Now cue the posts regarding harsher ride, deteriorated performance, etc...
Bigger wheels certainly could make the Sportage's ride assbad.
I made a thread on it a while back. If anyone wants large rims, it's only for appearance, since it compromises handling and comfort and price. Tire sidewalls improves ride comfort, and the suspension performance depends on geometry expected with OEM size wheels. As well, I have one car with OEM low-profile tires, and if I have to replace a fifth shattered 600$ rim, I'm buying all new proper-size rims & tires.
If anyone is interested in improving performance, there are lighter wheels than Kia's OEM.