My husband and I are both piano technicians and I can guarantee that rolling the piano on hardwood floors will gouge the wood badly. The edges of the piano wheels are very sharp and the weight is an issue - particularly if the piano is old and the wheels a bit rusty.
The best way to move it is to lift the piano. A grand piano weighs between 1500 to 3000 lbs. Three very strong men should be able to lift it a little to move if it is only a few inches. Another possibility is to place moving sliders under each wheel. Sliders can be purchased at Bed, Bath and Beyond, or any hardware store. Be sure to place the wheels sideways so they don't move off the sliders. It is easiest to place the sliders under each wheel by getting on hands and knees and lifting the piano with your back (or you significant other). It will most likely take two people to do this but my husband and I frequently place casters under piano wheels this way.
Finally, if no luck any other way- call piano movers. It will be cheaper than repairing your floor. I would also recommend placing casters under the wheels after the piano is positioned. This keeps kids from trying to push the piano around, hurting themselves on the wheels by getting their fingers pinched and most importantly disctributes the weight of the piano on more than just an inch of flooring. Many homes in CHicago are not reinforced enough to withstand the weight of any piano (even the smallest ones) so casters help to distribute weight a bit more evenly and prevent your floor from bowing inwards towards the pianos.
If you have any other questions, or need names and numbers of reputable movers, please feel free to contact me.