what's the diameter of a vauxhall astra K reg's wheel spanner?

I think you will find it depends on the year and the wheel type, but there are only two sizes:

I would not recommend a spanner though. A single hex socket and breaker bar are the correct tools for undoing and a torque wrench for doing them up.

Most car places also sell a purpose designed wheel undoing kit consisting of single hex reversible sockets in all the likely sizes with an extendible breaker bar, all in a bag for the boot, these are a very useful addition to any toolkit. The bar is extended to undo and shortened to do up (unless you are very weak the short size will do up adequately tightly) Approximate cost is 10 pounds, so an absolute bargain as well.

mrcheerful

If you want to replace the orginal, have a look in your nearest breakers. Jacks and wheelbraces are often left in cars when they're scrapped. Price circa £1. Mike.

Ruler? I'm not being sarcastic, that's what I would do.

well I've done that before and got it wrong somehow! (not on wheel nuts admittedly!)

ian

Nuts are 17mm or 19mm as stated. Aldi have a marvellous wheel nut wrench- extendable handle, reversible socket for whatever size, chrome vanadium and all for £2.49. German manufacture. How do they do it? DaveK.

The message from "davek" contains these words:

I'm surprised it's German - it may have all sorts of German approvals stamped all over it - Aldi are a German firm, but most of their stuff is imported from the Far East.