Which speedo gear for 3.23 and 255/60/15?

Sometimes it requires trial and error. Not all speedos are created equal. I used the chart for mine recently and I tried a 33T and then a 34T. At the end of the day one way +3-4mph and the other was - 3-4 mph so it was as close as I could get it.
I used the Waze app on my phone for comparison.

I also looked at a few different charts but all pointed to the same gear in my case.