From my end of the microscope, Loctite's a can of worms.
- Loctite reduces friction between nut and lug so I will overtighten the nuts beyond their design torque if I tighten by the stated amount,
- Which means I will be over stressing the lug, & the wheel.
- When I come to undoing the nuts, I need a lot more torque to break the bond between nut an lug,
- Which means I will be taking the lug & the nut beyond their design stress again.
- Plus the lug and the wheel will be beyond their design stress both when the vehicle is moving and stationary.
Time to put my engineer hat on. TLDR don't worry about it, just torque to the minimum recommended value (85 ft-lbs) if your threads are lubricated.
You're not wrong, but there's a lot of things to take into account when torqueing hardware. - yeah, a can of worms.
Normally, a positive margin is built-into any design. In the aerospace industry, our recommended torque is usually around 80% of the yield strength of the material. If the spec says 85 ft-lbs, you can give it more without causing permanent damage, however doing this repeatedly MAY eventually cause fatigue failure. This is because fatigue damage occurs at stresses below the static stress limit of most metals. For wheel spacers, you're only doing this once or twice, and that is less damaging than not using loctite and having get loose over time, rust, or gall. It's difficult to pin down all of the factors at play into an equation to determine proper torque when the friction is modified by water, oils, other contaminants, surface finish, or natural lubricity of the metal (plated/coated steel and black oxide have different coefficients of friction). This is why margin is built in.
From the loctite FAQ site
Frequently Asked Questions | Loctite:
When we apply threadlocker to a bolt, we tighten it by giving a tightening torque. The torque at which the nut can entirely be taken off is the breakloose torque. The main function of the threadlocker is to maintain the torque. It has been determined that over time, due to various factors like vibration, side sliding etc., there is a loss of upto 30% of the torque given to the parts. The goal is to select a threadlocker that would give you a breakaway value equivalent to 30% of the initial torque in order to maintain your torque over time. For eg: Let's say that a tightening torque of 10 Nm was given to the assembly. The breakaway torque (strength provided by the threadlocker) is 5 Nm. Now due to vibrations, there is a 3 Nm loss in tightening torque. So if you do not apply a threadlocker, your assembly tightened at 10 Nm will open at 7 Nm. Whereas, by applying a threadlocker, your assembly tightened at 10 Nm will have the total torque of (10+5) 15 Nm and even on 30% loss, it will open at 12 Nm, which is higher than your tightening torque. This is what is known as torque augmentation with LOCTITE threadlockers
That said, small hardware is much more sensitive to over-torqueing than the 1/2" studs were talking about here. Be very cautious about things like #10 screws. I personally use anti-seize on wheel studs but I torque them to the minimum recommended. Based on this post
WJ Torque Specs - Complete List the wheel lug torque recommendation is 85-115 ft-lbs. With the anti-seize reducing the observed torque by 30% (estimated), that brings the theoretical torque to 110 ft-lbs if I torque it to 85 ft-lbs, which still lies below the max recommended.