Wheel Nut Size

I have a problem with the Swollen Wheel Nut Chrome covers.

I have bought some new Wheel Nuts and managed to get the Chrome Cover off the offending wheel nut, however, the orginal wheel brace does not fit its now to big, does any one know what size Socket I require for the orginal Rusty Wheel Nut on the car? The largest Socket I have is 22mm so need to order a new Socket but would like to order only one then have to order several to see what size fits.

The wheel nut with its cover is 27mm.

1 inch is to tight to get on a nut without its cover...

Normally those covers only add 1-2mm, but to be sure.

1, Grab Ruler
2, Measure across width of nuts
3, Buy corresponding socket.