Is the up to 85% just for an hour or two or for extended times? Theoretically you can compensate a bit with enough heat and airflow, but 85% is really high if it's more than just a moment. Is the air outside the tent as high? If the tent has higher humidity than outside, just increase the airflow speed - with more output the air exchanges faster and should get closer to room RH. If the room is as moist, you might want to consider getting a dehumidifier for your tent (or room), and also try if open windows add or lower the RH, as depending where you live the air might even be more humid than indoors.
If your plant experiences these levels of humidity for extended periods of time, it is very likely you'll experience rot/mold issues and stress the plant with the environment. I would explore above mentioned options to bringing the RH down. Generally under 60% is safe zone if there's enough airflow but in flower for optimal conditions you want it closer to 40%. To look up ideal values depending on your temperature and grow/flower phase, you might want to check out VPD chart for cannabis. It's a great guide for the correct ratio of temperature v. humidity incl danger zones.