I can't remember ever seeing a "torque requirement" specified with no tolerance allowed.....
Most torque requirements are specified these ways:
85 ftlb +/- 5 ftlb or 85 ftlb +/- 10 ftlb (if a wider tolerance is allowed)
85 ftlb +/- 4%
85 ftlb (with no tolerance, but it's understood that the "applicable engineering tolerance" is allowed)
I've never seen any torque requirement, not even on airplanes and missiles that does not have a tolerance built into the requirement.
In the Air Force, torque wrenches are tested and certified by a Precision Measurement/Equipment Lab (PMEL). They test torque wrenches under strict temperature/humidity conditions and then certify them to be "within acceptable tolerance".
As an example, this link is to the USAF Technical Order that establishes the Air Force policy on torque.
https://www.robins.af.mil/Portals/59...14-3-1-101.pdf
If you go to table 5-1, you'll find an entry for 9/16 18 thread bolts. When torquing a "tension type nut" on that bolt, there is a "required specific torque".
It is expressed in the Tech Order as "800-1000 inch pounds". That can also be expressed as either 900 +/- 100 inch pounds or as 900 +/- 11%.
In some applications where the design engineers "prefer slightly more torque in a given application" they may express the specific torque for that bolt in another fashion, such as 950 +50/-0. Although this type of torque is usually only found in extremely critical components and CERTAINLY not on something like truck lug nuts.
I can't ever recall seeing a torque requirement without a tolerance and if it were to be expressed as such, where would you find a torque wrench calibrated to such exacting standards? As Jim noted, even NASA doesn't have torque wrenches calibrated that precisely.
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