Though your car may look better having bigger rims, there is a lot of discussion about the positive and negative effects of having bigger rims.The positive effect being that your car may look better depending on the size of it. Sometimes the extremely large ones are not that fun at all.
Having bigger rims does have quite a bit of negative effects, like additional weight to the entire vehicle. So after customizing your car to fit the rims, you'd have to customize it again to compensate for the weight of the vehicle. Some additional changes would be needed in order to maintain the performance you had before changing rims.
If the rims were not properly installed and was not fitted correctly, it may cause the tire to hit the fender and suspension and the fender during tight turns.
Having bigger rims also does affect the speedometer, if you do not have the correct tire height for the specific size of your rims, reporting slower speeds than it actually is. Though this is a minor problem and already has several fixes to correct that.
One negative that I found is that bigger rims cause lesser fuel mileage. Though I don't really have evidence or research to support that, it might be important to note.
Bottomline is, if you want to improve the appearance without concern for performance issues, it is ok to have it larger as long as you have professionals to install them. As sometimes things depend on the size of the rims if your car need's additional customization like cutting the fender to fit the tire. If performance is a very big issue, and still would like to have bigger rims, additional customizations would also be needed to further support the bigger rims.
