Xli 2002-2007 came with stock 175-70/14 General tyres and on it's door stickers alongwith this size 185-65/14 was also written. After the purchase I immediately changed to Yokohama A300 185-65/14 and the ride became so noiseless. Three years later I switched to Dunlop Eco 195-70/14 and it gave me good grip, improved breaking and a comfy ride.
Now the tire calculator says non-stock tire is 4.7 percent slower
When speedo reads 100 kph, you are actually travelling 104.7 kph
I think that when you revert to stock size the speedo should also be back to normal.