I'm not sure where you are coming up with that number. The chart starts at 30 psi which might be appropriate for 66 lb load on the rear tire. But if for an 86 lb load, the pressure should be around 40 psi. But I think the chart's pressure are far too low for the load they are carrying. At 30 psi or even 40 psi for a narrow tire like a 37mm, the bike would corner poorly because the sidewall would flex too much. And that probably wouldn't provide much protection against impact. In other words, the wheel would be at higher risk for damage during even a marginal impact as well as the tire more prone to snake bites.

Yes, it might provide a comfortable ride but if you are fixing flats all the timeit's not worth the comfort to risk damage to tires, tubes and wheels. Remember that TJohnson is experiencing snake bites at 90 psi, reducing the pressure to 40 psi wouldn't improve his situation.

Personally, I wouldn't run 30 psi in a 55mm mountain bike tire which has a whole lot more volume.