I agree that there will likely be little weight difference. Alloy wheels will tend to be straighter, and in my experience are tougher, handing curb hits with cosmetic but not functional damage. My current small trailer has steel wheels, but if buying new I wouldn't get more steels. All of our other vehicles - including the motorhome and the larger trailer - run alloy wheels (all original equipment or extra sets - bought used - of original equipment wheels).
I agree - I would get the full set. Rotating (with the spare in the rotation) is useful, because if you don't you may end up either running an ancient spare, or throwing out a perfectly good spare tire based on age. My current trailer has a mismatched spare which I should replace, as I certainly wouldn't trust it.
I suspect that changing to any other wheel would have fixed the problem. Since the rim portion of a steel wheel is typically one piece, the only reason I can think of for a slow leak due to the wheel would be a deformed rim in the bead area preventing proper seating of the tire on the rim. Back to my point about alloys being straighter...
Good point... we really don't know what the problem was with those original steels - just remounting the same tires on the same wheels might have fixed them.
I can't imagine surface rust on a wheel that looks like an alloy, but I suppose some people don't really have any idea what they're looking at. A recent trend is to steel wheels with chromed plastic covers so thoroughly integrated with the wheel design that they really do look like cast alloys until you get up close, but those wouldn't show rust on the front (because the plastic doesn't rust)... and I personally have yet to see one of these intended for trailer service.
Chrome is just the plating, and the wheel underneath can be steel, aluminum alloy... or the integrated plastic cover. Chromed steel often have problems with peeling or pitting chrome.
They're all functional, so this largely an appearance choice, and for some vehicles (partially) exposed steel wheels are better suited in style.
I mis-read this the first time and had it backwards! Since the problem was with alloys, the likely culprit would be porosity: tiny holes in the metal of no structural importance which leak air. I've never experienced this, but then I generally use genuine original-equipment (Toyota, Honda, Ford... and Alcoa) alloys. They're typically not particularly light or stylish, but they are built to not have problems. I don't know which small "trailer wheel" brands would be good.
