General rule of thumb is that for every 11 Watts of power you add, you should add 10-15 in/sec to your speed range. So for. 4m drive you should run 40-60 in/sec.
Formula for speed is
RPM x 3.14 x wheel diameter(in) / 60 = speed (in/sec)
Do some algebra and you get
Wheel diameter (in) = speed (in/sec) x 60 / (RPM x 3.14)
Simply to get
Wheel diameter (in) = speed (in/sec) x 0.0425
Now plug in values of 40 and 60 in/second to find reasonable wheel sizes.
I find a maximum wheel diameter of 2.55 in/s and a minimum of 1.70 in/ sec.
In conclusion, if you want to run 450, use 2 inch wheels. However, word of warning, the 48 tooth gears used to achieve 450 rpm are about 1.9 inches in diameter so depending on robot weight and number of wheels, you may find your gears sinking into the tiles (bad).