Cobra Trailer Wheels

I could not find that Cobra offers aluminum wheels as an upgrade to the steel wheels with hub caps. Is there a European safety reg or something with trailers with aluminum wheels? Seems kind of old school to have steel wheels with hub caps with a nice trailer that cost so much.

Does anyone know if the bolt pattern is unique and if there is a aluminum wheel as a good replacement?

Reason I ask is I looked at a few trailers at a dealer and forgot to ask him about the wheels but I looked on the Cobra web site and they have no mention of aluminum wheels.

Wonder how many people actually use the old school hub caps anyway? Seems like a waist to me.

Thanks
Casey