What causes lug nuts to loosen up?

I have a brand new 2018 Cascadia with 18k miles on it. Twice in 4 days, I've had to bring it to a shop to have the lug nuts tightened on it. It has aluminum rims all the way around. What could be causing my lug nuts to keep coming loose?

 

Inadequate torque on the re-torques

Temperature changes (expansion rate of steel and aluminum is different)

Since you say its new, wonder if the studs are stretching? Overtorqued maybe?

 

Should be torque to 450 far as I know?

 

Good job catching the problem.Once all are a little loose they snap causing disaster.Some claim previously over torqued and stretched lugs being properly torqued will loosen up. I wonder about this myself.With a new truck shouldn’t be your problem.If it’s on the same wheel 2 times Id be concerned. If it was the steers maybe they were removed during Transport then improperly re installed.I’m sure you had them check all 10 for proper torque. They have some safety products to keep them from moving also cheap plastic arrow shaped things that slip around lugs for an easy visual inspection for movement. Right now is the time to emphasize your concerns with Dealer. Make a little noise, maybe they can help with added cost or at minimum parts for cost and free labor to install. Emphasize the word Liability.

 

Torquing aluminum wheels is critical even on passenger vehicles. Here in Ontario you have to be certified to install a wheel on CMV or any vehicle at a commercial shop.

 

Another thought:

If those wheels have been off recently the mounting surfaces may have gotten some mud or dirt trapped in between them and the hub?

 

Part of trucking. I've been driving trucks since 1999. I have my own tire truck to do roadside repairs. I worked in the heavy tire business for 6years.

Lug nuts will loosen up sometimes.
Heat. Potholes. Cracks at 70 mph they will come loose.

 

So, originally it was the left rear that was loose, today it was all but the right front drive, including the left rear, again.

 

If they are hub pilot, would too much thread lube keep them from staying tight?

 

Yes,I thought after 150 miles new...you retorque em...then theyre good? How many drivers carry a torque wrench capable of 450 ft lbs. Is this even possible "manually". Seems excessive.