Need help selecting tire size

[wildroot]

My son recently purchased a '07 Yaris hatchback and it's in need of a new set of tires. The last owner put 18" rims on it with 215/35/18 tires. The tires are trashed and the ride is horrible...no doubt the low profile tires. If we stick to 18" tires, is there room to up the profile a tad? There's not a whole lot of clearance now so it wouldn't be able to be much.

The other option is to buy some 15" or 16" rims, but I know he likes the look of how the wheel well is filled up with tire, minimal clearance etc...If we went with the 15' or 16" rims, what size tire would look good on the car and perhaps split the difference between a low profile tire and the stock look. It's all about the appearance, right?

I was looking at 205/50/16 but wasn't sure if that'd leave huge gaps between the tire and the fender well.

Thanks