Had a post from the owner with the following facts presented.
Michelin XZA2 Energy 295/80R x 22.5 Load range H
Steer axle scale weight is 14200 (tire placard shows 110 PSI closest)
Drive axle scale weight is 17360 (tire placard shows 75 PSI dual closest)
Tag axle scale weight is 7800 (tire placard shows 75 PSI single closest)
Total gross weight is 39360 per scale
MFG front GAWR is 14600# max
Intermediate GAWR is 20000# max
Tag GAWR is 10000# max
GVWR is 44600# max
OK as an Engineer I always feel Facts & Data are our friends.
Using info on Michelin web site, and assuming perfect 50/50 side to side balance (unrealistic) I come up with F@110 psi which gives you a 2.8% Margin on load capacity
Drive & Tag 75 psi for a 8.9% and 27% margin
However if we assume a 45/55% split which is more reasonable
F @ 120 we get a 0.3% margin
Drive at 80 psi gives a 4.8% margin
Tag @ 75 gives a 20% margin
Note I suggest that in a perfect world that once you know your actual individual axle end load, you use the tables to find the minimum cold inflation and then add 10% to that number for your morning cold "set" pressure.
those smart enough to run TPMS, I would set the warning level to be the
minimum cold inflation and not just the standard 20% below the morning
"set" pressure. With the proper TPM system that gives not just the low
pressure warning but also a rapid air loss warning you have a good
chance of coming to a safe stop before damaging the tire or its mate
from driving when officially flat i.e. having lost 20% from the minimum
needed based on actual tire loading.
Hope this helps.
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