changing a tyre?

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anewman wrote: »

I think most car manufacturers advise against it in their manuals, but it is common practice to help stop the nuts seizing. See this google search http://www.google.co.uk/search?source=ig&hl=en&rlz=&q=copper+grease+wheel+nuts&btnG=Google+Search&meta=

It stops something called bi-metallic corrosion occurring which basically means that two different types of metal in contact will rust together and seize making it difficult to remove...............

It is not normally the nuts seizu=ing that's the problem. It's because they have been fitted with an ir hammer and the operator has not set it to the correct torque. basically they are overtightened. This can be a problem as it can and will stretch the metal studs or bolts which weakens them.

Bimetallic corrossion is not normal as the studs and bolts/nuts are normally made from steel (i.e. they are both the same metal) You may sometimes get a reaction between alloy wheel rims and the steel, but that would not normally cause this problem. More likely good old fashion rust!!

I would recommend that whenever you buy a car or have a wheel changed at a garage or tyre fitter's you immediately check the wheel nuts with your normal wheel brace/wrench to ensure that you can undo them. It's easier to get them sorted before the puncture on a cold wet night on the motorway. Also remember that wheel nuts generally do not need to be so tight that you need excessive force to loosen them. If you do not have a torque wrench then do not tighten them up to much more than finger tight and then just “nip” them a fraction more with your wheel brace/wrench. Generally that will be sufficient. If you check the torque for wheel nuts it is generally on most family type cars not as great as you would imagine