Self loosening lug nuts?
 

Not directly miata related, but not sure where would be a better spot for this?

Cars, 2011 Honda Fit with Kosie K4R wheels and the included closed top conical seat lug nuts from Tire Rack, 2003 Pontiac Montana with stock alloy wheels and original GM lug nuts.

On my Fit, any time I put the K4Rs on and torque the lug nuts, they need to be retorqued after 2 miles (usually all are loose), then again after 5 more (usually 1-2 loose on each wheel) Then for the next few drives after every drive (usually 2-3 loose on whole car), then check them every other day for the next week (usually below torque, but none actually loose). After that, they are generally good. Though I check them about once a month, occationally finding 1-2 loose. This is torqueing them to 95ftlbs in a star pattern.

I make sure they are sitting flat when I put them on, tighten in a star pattern with a drill while in the air, then with a 1/2" drive socket wrench before putting the car down and torquing it.

I usually torque alloy wheels to 80-85ftlbs. This has prooven fine on my other cars, including the Miata while doing track and autocross. Steel wheels I will do to 95ftlbs.

The Montana gets 110ftlbs per the instructions, needs a retorque after 5 miles, then usually again after the next drive, and then again a few days later. My dad usually drives the lug nuts on with the impact set way low (usually ends up around 50-60ftlbs) before putting the car down and torquing them.

These same cars get steel wheels in the winter with no problems with the lug nuts coming loose. None of the other cars in our fleet have ever exhibited this behavior.

The torque wrenches have been checked against each other and a beam type and all read the same.

What is going on that causes this?

Sounds a lot like a De Matta.

You have lost me.

Why does your dad do this instead of you?

Because I use my drill since I tend not to want to drag the air tank out. It is just to spin them on quick, not for torquing or anything. Just putting all the data I can to make sure I am not doing anything silly.

The only thing you are doing that would be considered silly is driving a Pontiac and a Fit.

are the angles of the centri cones the same?

They look to be. Though I will check tomorrow with a closer look. I highly doubt tire rack would screw up and provide the wrong lug nuts? On the Montana, they are the factory lug nuts and rims, so they darn well better match.

For the Montana, it's what Ma wanted. And if Mama ain't happy, ain't nobody happy. It has lasted 13 years and 170k miles so far with only a few minor electrical gremlins. Not complaining at all.

The fit has it's problems, but it makes up for them in being exactly what I want for practicality.

if its not the seats being wrong, and not over application of antisize on the threads getting onto the seats then the threads themselves are probably worn out and new studs and/or nuts would fix it.

Yeah that would be the only other logical thing.

Haven't put antisize on the studs until last year. I put these wheels on when the car was about 1 year old and had had the wheels swapped 3 times by then. They have done it since new. So that rules out worn nuts or studs and antisize. Same thing with the Minivan. It has done it since it was new back in 2003.