Swollen Lug Nuts Are Driving Tim Nuts

Dear Car Talk

Dear Car Talk | Nov 01, 2016

Dear Car Talk:

I own a 2014 Toyota Sequoia and took the car in to the dealer for its 35,000-mile oil change and maintenance -- including a tire rotation. The service manager called to tell me that everything was done and in good shape, but that he had to talk to me about something. Needless to say, I was curious and just a bit concerned.

When I got there, he told me that my lug nuts were swollen. I had never heard of such a thing happening. He told me that the lug nuts are made out of two different metals and that this swelling often occurs. He recommended replacement, but said it might be OK if I went to an auto-parts store and bought the new lug nuts myself if I wasn't comfortable paying the $14 apiece for the 20 factory originals ($280!). He indicated that there is not a safety issue, but said they have to use a socket one size larger than normal, and therefore, my lug nuts might become scratched. I wondered why I would buy factory originals only to have my lug nuts swell up again, and asked if I should contact Toyota to see if maybe it could replace them with non-swelling lug nuts that would have been more properly engineered.

So, Ray, do I have a valid beef with Toyota? Is there a safety issue, or is this indeed just a cosmetic thing? Where can I buy lug nuts that don't swell?

-- Tim

Whatever you do, Tim, don't put BenGay on them.

These lug nuts are indeed made of two different metals. There's the lug nut itself, which is steel, and then there's a thin, chrome-plated metal covering, which is entirely cosmetic.

Because the lug nuts on this truck are exposed, Toyota wanted to make them look nice and shiny, rather than rusty and ugly -- like most lug nuts. So they covered the nuts with a chromed sheet metal. We've seen a lot of cases of swollen nuts in the shop. Usually, it tends to be associated with older cars; it's not something we typically see on a 3-year-old vehicle.

What happens is that moisture gets in there and begins to rust and swell the steel nut, which then pushes on the chrome nut-cover, making the whole thing enlarged.

And while it's not a safety issue per se, in that your wheels are going to fall off, it is a safety issue in that the lug wrench that comes with your spare tire won't fit over them anymore. It's supposed to be a 21-millimeter nut. But now yours are 22 millimeters. And if you have a flat tire in a remote location, that lug wrench is going to be unable to grip the nuts.

Or, if there's a lot of rust underneath, the chrome cover can actually break off, and you'll be left with smaller nuts than you thought you had. Not to mention less-shiny nuts.

So I would complain to Toyota, Tim. At 35,000 miles, you shouldn't have to spend nearly $300 to replace something that should last the life of the vehicle. If Toyota turns you down, then, as a backup measure, I'd buy a breaker bar and a bunch of sockets. I'd get a 19-, a 20-, a 22- and a 23-mm socket. And I'd throw all that stuff in with your spare tire.

That likely will cover any swollen- or delaminated-nut scenario you encounter with a flat tire. But I would hope that Toyota will take care of you. Unless you're parking in a salt marsh, this sort of nut-swelling shouldn't happen on a car of this age.


Get the Car Talk Newsletter