The point of these is to have small differential, when line is IDLE. So anything will do.
Use ~10k values, to save power :)).
You can choose values in a such way, so IDLE voltage diff on your line would be ~0.2V
Then it will be ok: your line is not floating, when IDLE.
The lower the resistor value, the lower is the cable timing characteristics, the more immune it to the noise, the more current it consumes.
BTW i would like to see a workplace which causes noise to an RS485 line. Welding workshop, where you weld and test huge antennas 
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