I was under the general impression that steel wheels used different wheel nuts to alloy wheels. I do not know if this applies to the jazz. Hopefully someone that knows better than me can advise.
FredS
My steel space saver wheel uses the alloy wheel nuts. A standard steel wheel could well use nuts with a different shaped mating surface. You could check the part numbers for steel and alloy wheel nuts.
alloys and steel use 60 degree taper nuts, except I believe some VW group (why ? they don't need a reason, it's just because they are German) my brother mentioned 'a hemispherical shape on his Skoda Octavia - and they use bolts instead of studs, bad luck if thread strips in the hub........
(also because the bolt screws into / through the hub flange into an open ended hole (rather than a stud with a closed 'acorn' nut) I'm supposing rusting of the thread making it hard to get bolt back out may be a problem).
I regularly swap steel and alloy wheels on my wifes Jazz and my Civic - all I did first time with the domed Chrome (Acorn) nuts was measure the length of stud sticking through the steel wheel (steel wheels are thinner than alloys) and make sure there was enough depth of thread in the nut so that stud did not 'bottom out' - there was plenty of depth.
Most if not all alloys have a steel insert cast in to take the nut angle, I think maybe a long time ago alloys didn't have this and had to use a different taper or shape to steel nuts because the alloy was softer than steel and was maybe liable to split or crack with 60 degree nuts.
When a centre spigot on the wheel hub is used which is a very good fit into the hole in centre of wheel (almost universal these days) this takes a lot of the load off the studs and makes sure the wheel is running perfectly central to the axle.