225/60R15's will be a good bit smaller than the stock 225/70R15. They will look rather dinky on there, and while they might be safe, running a smaller diameter tire messes with the gearing, making for higher engine RPMs at a given speed compared to stock tires. This isn't much of an issue on models with a manual shift transmission, but can affect the performance of an automatic. Besides the speedometer and odometer being off, it will cause the odometer to register more mileage, meaning it will rack up the miles from the tires spinning faster, even though it's actually gone much less.
I would either stick with the stock 225/70R15, or find a closer alternative size like 255/60R15, 235/65R15, or perhaps even the optional stock size of 235/75R15.
