Actually, the 185 tires are about 2% larger diameter than the 175 tires, but it should be OK if they are are kept on the same axle. As others have said, put the new tires on the back and replace the front tires with the matching size when they wear out.
When you have good tires on all four wheels, you can have them rotated every 5000 miles or so. Most tire shops will rotate them for free when you buy their tires.