Diameter is close enough that the speedometer won't bother me.There are going to be a few factors to consider.
1) is overall diameter close? If not you’ll need to reprogram do the speedometer is correct.
2) is the load eating the same or grater?
3) is the rim width ok for the narrower tire?
4) are you willing to give up handling with less tread on the ground and a taller sidewalk?