Alloy wheels are always lighter than steel.. I have had no problem with my spare 33" on the stock carrier.. I did shim the carrier out on the bottom, about an inch, and used longer grade 8 bolts so the tire would clear my rear bumper.. 78,000 miles, and lots of off roading, and still no cracks or rattling.. Just be sure everything is snug up against the rubber stops..
04' Rubi, with all the gizmos we need for long range excursions, / home modified excursion trailer;
96' Lexus 450, locked, loaded and ready to roll..
'12 VW New Beetle