Thank you for your question.
Sorry for the delay. It took me a minute to ascertain the codes for Oregon.
Well as in any circumstance such as this I would always advise you to check with the local inspections department and ascertain what is code for the locality in question and also how the code is interpreted by the inspector there. After all they have the final say so in matters such as these and can offer any scenario for allowing a variance etc.
Having said that, the Oregon code states that the maximum allowable height for a riser is 8 inches. Note this is the maximum allowable. In my opinion something more along the lines of 7" to 7 1/4" is most comfortable. Depending on your specific application will determine the overall height required for your project.
Below is a link to the Oregon codes. If you click on Chapter 3 and scroll down to section R3126.96.36.199 you will be able to view the current criteria for stairs i.e. riser height, tread width, handrails, headroom etc. The commercial codes for stairs will most likely be identical for riser height etc. but call the inspector first to make sure. I think you will find this information helpful, however you should still contact the inspections office to ascertain any differences before you start any actual construction.
I hope this answer is helpful and good luck with your project.
Oregon code information here