I live in an apt building too, and it's simply not allowed to work on cars in the garage. Doesn't sound like a good place to work in even if you are allowed tho, plus you'd be inhaling exhaust fumes from the other, non-electric cars. Just take it to a place that specializes in wheels in that case.

BTW, nothing wrong with 18" or 19" wheels, usually they will be lighter at the same price point (i.e. a $300 wheel, per wheel, should be closer to 19 lb., whereas 20s at that weight will cost you an arm and a leg); if you put equal tires on them (i.e. MPS4Ses), the 18s may even outperform the low sidewall height 20s, and provide significantly better ride comfort. Once I shred thru the OEM 20" MPS4S tires that came with my car, which shouldn't take too long to do, I am definitely downsizing to a lightweight 19" wheel (and putting the same high end summer-only tire on them).