alloy wheels?

Impossible to answer that..........
aftermarket wheel weights are all different......some will be heavier(usually cheap wheels) and some will be lighter(usually expensive wheels).

(Edited)

Not necessarily, but most of the time cheaper wheels are heavy. Axis maglites are pretty cheap and weigh under 15lbs, and my Momos are hella expensive and weigh over 25lbs. Look at I-forged wheels they are up to 35lbs, and cost over $3,200.

I was referring specifically to the alloy wheels that are an option from the factory.

Oh. The alloys are probably at least 5 lbs lighter compared to the steel ones.

Oh. The alloys are probably at least 5 lbs lighter compared to the steel ones.

anyone know for sure?

According to Scion the xB alloy wheels weigh 7.6kg, or 16.7 lbs. They wouldn't / couldn't give info on the stock wheels but other mfg's 15x6 steel wheels weigh in at 18-20 lbs.