A bit surprising but if you aren't racing or hard core off roading I wouldn't have a problem with it. The load is spread out pretty even on the tire bead. some quick napkin math shows an estimate of 5500# of force on the bead and 58" of bead on an 18" rim meaning a static load of less than 100# per linear inch. A weld in aluminum thick as a rim can easily handle that.

28" wheel diameter minus 18" rim diameter 30psi was about 11,000# force. Half held by the tread half by the rim 5500# ish.

If the rim is already dealing with 11000# of force (both sides) the additional weight of the car is only 11-15% more than when lifted off the ground. Impacts like pot hole will likely not amount to much more than double the weight of the car so 22-30% more than static load. The sidewall will act like spokes to distribute the load evenly around the rim so you don't have to worry about that one spot taking much extra load when hitting the bottom.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)