Wheel studs breaking off

I have a 2018 Subaru Impreza. I use snow tires in winter, and last spring when we took the snow tires off we found that 2 of the wheel studs on the front passenger side had broken off some time after we put the snow tires on. They were covered by the wheel covers and we didn’t realize there was a problem until we changed the tires. We had brought the car to the dealer for a wheel alignment after putting the snow tires on so they were the last ones to touch the wheels and we assumed that the dealer had over torqued the studs and caused them to fail. I recently found that 2 wheel studs have broken off on the front driver side, so now this has happened 2 years in a row. My husband put the snow tires on using a torque wrench so we know he did not over torque them. The car was at the dealer after he put the tires on and they did a multi-point inspection, so it is possible that they removed the wheels.
Now that this has happened 2 years in a row, both times in winter, I need to figure out what the problem is and how to prevent it from happening again. My snow tires are on steel rims and my summer tires are on aluminum rims, and I’m wondering if the steel rims could be part of the problem. I am also wondering if corrosion from road salt during winter driving is contributing. I have driven the car without wheel covers during part of the winter so perhaps the wheel studs have been exposed to salt. I’m also wondering if this is a particular problem for Subarus, as this is my first Subaru and I’ve never had this problem before. I would appreciate any suggestions.

If that inspection included the brakes, the tires would have to be removed because the steel wheels would block the view to the brake pads.

And if that’s the case, one would assume the lug nuts were over-torqued causing the studs to stretch and fail.

Tester

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If they were broken and covered by the wheel cover… Didn’t they rattle around and make a noise?

I’d agree the dealer is pretty likely the problem.

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Ya - a lot of shops just whale away on lugs with an overpowered impact. Terrible practice, be we know they do it.

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I’d have all old studs replaced on both front wheels.

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Agree with replacing all the old studs. If only ONCE did the dealer wail away at the studs, there certainly will be others right on the edge of breaking.

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It is unusual to have to remove a wheel during a wheel alignment. Depending on the type of wheel mount used with the alignment equipment, the wheel coves may not have been removed.

Most brake pads can be inspected for wear/thickness from behind the wheel, while under the vehicle performing the multi-point inspection.

What to do? If you continue to use the same places to do your automotive work, the next time you take it there let them know about your concerns. Request that the wheels are put on using the proper torque. They will probably say that they always do, but they’re probably lying. Mention your concern everytime you go in so that you are known as the wheel torque person. Or you can find another shop to do your work. No amount of road salt or contaminates can cause stud damage to this extent in 6 or 7 years. For this reason, it is also very good advice to change out all the studs.

Unilikely. When I lived in Colorado my snow tires were on steel rims, in fact I have never used anything else than steel rims, Colorado or Calif, & I’ve never had any problematic wheel studs.

For the most part I do all the wheel removing & installing myself, using just a breaker bar and socket. I coat the surface of the studs with a little moly-lube to help prevent corrosion.

As far as what you can do, I think the idea to replace all the remaining studs is a good one. And whenever a shop installs a wheel, when you get the car back home, loosen the lug nuts and retighten by hand.

My wife drove a 2015 Subaru Crosstrek for 6 winters (northern MN - lots of salt) with winter tires on steel rims (aluminum wheels during the rest of the year) and I never had an issue with studs when swapping back and forth but I always torqued to spec (89 lb-ft - same spec as your Impreza).

This is why, when I’m going to a place to have something done that requires wheel removal(rotation, brakes, etc.), I carry my own torque wrench and socket into the front office or reception, and the employees present know I mean business!

They’ll, some times begrudgingly, low-power torque the lugnuts, and let me check-torque my own wheels.

One place I went to insisted that no technician is allowed to torque wheels under 100 ft lbs, for safety and liability reasons, “even if you as the customer insist”. My 8th Gen(2008-12) 2010 Honda Accord lists 80ft lbs of wheel lug torque.

If you came into a shop i ran with your own torque wrench you’d be told to leave and not return.

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Why that attitude?

I, as a customer proud of and trying to maintain my car as meticulously as possible, want to ensure that the wheels lugnuts are at or just above the manufacturer’s torque specs, and that would piss you off as a mech?

After hearing so many stories of lugnuts torqued 50-100 ft lbs over spec, can you blame us?

Apparently you don’t trust my work and there is a good chance you will be a problem customer.

I don’t want to deal with you, you can go somewhere else and let them deal with you.

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If you came to my shop and demanded that I use your torque wrench on the lug nuts, I would tell you to get back in your vehicle and don’t come back.

I don’t know the last time that torque wrench was last calibrated/certified.

Or in other words, don’t tell me how to do my job.

Tester

I’ve never had mine certified or professionally calibrated…But I do check it out once in while with a digital fish scale. I check the fish scale against other stuff first (e.g. like fitness weights for the higher end and grocery store packages on the low). Measure out 12" on the handle - go low and slow. It’s an imperfect process but it gives a pretty good idea.

I’ve not carried it into a shop. But after a car is back from the shop where the wheels came off, I often do loosen and re-torque.

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I know very little about aftermarket wheels, but are you sure the winter wheels fit your car properly and the lug nuts fit the wheels properly? If something is wrong there, I’d imagine things could break over time.

Regardless, as others have said, I’d replace all of the studs now to be safe.

If the lug pattern was off, there’d be no way to mount wheels at all. They could be off in other ways (like the center bore or offset) but it’s unlikely to cause such an issue. Maybe the center bore, but very unlikely.

Apparently there are some of us who need to brush up on our reading comprehension.

Nowhere did I say that I wanted the shop “to use my torque wrench”.

What I said was: Torque my wheels to some low value, unrack the car and park it, and let me torque to spec with my own wrench.

And again: Maybe it’s only 1 out of a 1000 cars that this overtorqueing leading to damaged studs, but those incidents get heavily published, and I don’t want to take chances.

That said, and because of liability reasons I previously mentioned, if you all would read, the vast majority of vehicles on the road are rolling on lugnuts that are torqued waaaay over mfg. spec, some even 150-200 ft lbs. Airbus or Boeing territory!

I apologize if any reputable, good mechanics get lumped in here, but I’m not your average car owner, I’ve read through the manuals and am aware of certain specs, and I take note of what I do, and mechs. do, on a car.

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I’ve owned 3 Subarus, using both the standard alloy wheels and steel wheels for winter tires, and I never experienced any broken wheel studs. But, whenever I had tires installed or rotated, I always loosened the lug nuts when I got home, and then torqued them to the correct spec.

I think that this is a clear case of someone overtightening the lug nuts–likely on multiple occasions.

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