You should be able to put wider tires on the stock rims but make sure if you do so that the overall rolling diameter stays the same.
Front tires (155/60r15)- 22.3"
Rear tires (175-55r15)- 22.6"
If you change these measurements, you could change the speedometer accuracy to your car.
I'd wait until the 'Rack' has a 'plus-one' option for these tires. That way you can upgrade to a wider tire without affecting anything.