Most "blowouts" are actually slowly developing events. The tire has a puncture or some other issue that initiates a slow leak that goes unnoticed. As the pressure slowly drops the load capacity of the tire rapidly decreases and heat is increasingly generated until the tire fails catastrophically. The worst is an event that causes an air loss that stops just above the point you feel it and you are on the big slab itching to get to the appropriate exit. A recipe for disaster - especially 2 up. You have a false confidence from the diligent pre-ride tire check and the right wrist starts to pour on the coals. It would have been much better if the air loss had continued to a noticeable point before the heat nuked it. Even riding the twisties would be better because you notice the loss at much higher pressures. This is exactly why I think tire pressure sensors (with alarms) are such a great application on bikes, especially heavy ones like the FJR.
Consider this:
Tire reserves are preferred to be at least 50% for continuous cool running and best wear. I have included an R6, whichh uses the same size/load tire, for comparative purposes.
R6 - rear tire capacity (@ 42psi) = 806 - 210(1/2 wet weight) - 130(65% of 200lb rider) == 466lbs RESERVE
466/805= 58% TIRE RESERVE
FJR - rear tire capacity (@ 42psi) = 806 - 330(1/2 wet weight) - 130(65% of 200lb rider) == 346lbs RESERVE
346/805 = 43% TIRE RESERVE [[now drop to 38psi] - 276/736 = 37% TIRE RESERVE
ADD 40lbs luggage *****
306/805 = 38% ...........@ 38psi - 236/736 = 32% ........... @ 32psi - 170/670 = 25%
ADD 40lbs luggage & 140lb passenger ****
166/805 = 20.6% ............. @ 38psi - 50/736 = 6.7% .............. @ 32psi - -16/670 = -2.4%
Plug in your own numbers and do the math. It is easy to see why BMW uses 980lb 70series bias tires on their RT & LT.
The FJR being true to its sport side uses true sport sizes. While this works well solo or lightly loaded it requires some understanding 2 up and trunk and panniers stuffed. For those situations you have to become a pilot and start trading fuel for load or at least understand that triple digits may best wait until you are carrying a lighter load or at the very least the second half of the tank. Personally, if I find myself trimming the reserve a bit I will run 44 in the rear. I do this understanding that there is an unmentionable (by tire companies) margin of strength built in. This will cause center wear and longer braking distances but I can accept that if I am aware and adjust my riding style accordingly.
Wouldn't it be nice to know if you're going 85 to know that in the last 20 miles you have dropped from 42 to 39psi and that your tire that was running 120 degrees F is now at 140F even though the day is cooling off? Maybe it's just the pilot in me coming out and I need more gauges to play with.