[msej449]

Actually, a missing lug nut, to use the correct term. Should I be worried? Just back from the garage after a routine Summer Check ahead of a month touring the Alps, and they found a rear lug nut missing i.e. only 4 nuts in place, and one (a locking one) not there. Last serviced and MoT* only a month ago, so it must have happened in just the last 4 weeks.

I'll take it back to the independent who does my tyres and winter/summer wheel set swap, just to have them all checked. A few days after doing a swap, they drop 'round the house and check the nuts with a torque wrench, so I'm surprised that it could have worked loose.

These would be the original nuts on the standard OEM summer wheels. And they have been off the car every winter when the winters have been fitted. I suppose this does mean more cycles of removal/replacement than if they were on all the time, so perhaps more prone to failure?

As I said, should I be worried?

[*MoT - UK cars 3+ years old have to have an annual vehicle and emissions inspection checkand certification. Obviously, it would have failed with a missing bolt.]

[aerobod]

They are lug bolts not nuts fitted as standard from the factory.

Unless the bolts are over torqued at some point, dozens of wheel swap cycles should not be a problem. It is best practice to re-check wheel bolt torques within a few hundred kilometres of a wheel swap or before and after a major heat cycles such as with track driving. I swap wheels on my cars up to 20 times a year and have never had a wheel bolt or nut work loose.

I expect the last time your wheels were swapped, the bolts either weren't done up with the correct sequence leaving the wheel unevenly torqued, or due to it being the locking bolt that was loose they meant to use the adapter on it but forgot or didn't bother.

[msej449]

Just to wrap this one up - I took the car in for checking and all the other bolts are tight. So a one-off, as @aerobod suggested, seems the most likely: I'm suspicious that rather than at the summer swap-over, it's more likely to have happened last month, when it went into the dealer workshop for its 3-year service and warranty check, plus MoT and to have the floating hub caps fitted.

Either way, an object lesson to check my bolts at least once a month, perhaps.