Yea you can do that. but it is hard to tell that way. Try telling the difference between 4.10, 4.30, 4.56, 4.88.
For example 4.56. 1 turn of the tire = 4.56 turns of the drive shaft. Going to be hard to tell the difference between those ratios. The best way is to count the ring teeth then count the pinion teeth. Divied the # of ring teeth by the # of pinion teeth. = your axle ratio.