OEM Wheel Locks

You have to check. From what i see some will be 17mm and some will be 21mm depending on the production date. Thats easy to find if you have tools, you just have to check which socket fits.

or you can call your dealer and ask them. The mazdashop link I posted earlier has a list of vin number you can check against, but even they say you should call them to confirm.
 
So does anyone know - are the wheel locks for 2021 CX9 - 21mm or 17mm?
You had BETTER hope the nut size is 21, otherwise if you try changing a flat on the side of they road, you'll be in for a rude awakening when your lug wrench doesn't fit.
 
My key stays in the glove box. I have never lost one. They also give you a code that you safekeep to order a new key.

But yeah if you can’t trust yourself with the key, then don’t install the locks.
Not sure if keeping it the glovebox is really secure.
I'm guessing most thieves know that people put the key in the glovebox, and if they want your tires/rims, they'll just smash the window.
 
If they smash the window, they might as well take the wheels with it.

Kidding. It’s not as secure for sure, you can keep it with the spare tire or somewhere else in the trunk. But if you ever want to use your spare tire, you need the key in the car for sure.
 
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