55s would be OK, however the biggest downfall to the stock 16" tires is their economy bend, mine came with Bridgestone Ecopias that sapped a lot of fun out of the car. The stockers are meant to achieve that crazy 30 City/41 Hwy MPGs. Replaced them with Falken Ziex950 A/S and had a world of difference even at the same 60 sidewall ratio.