Speaking from experience - my rear wheels are a little tight against the caliper (about a business card space would make t clear!) and the previous owner installed those spacers (or similar); Probably right at about 1/4 - 3/8"; the lugs were only about half way on the studs. Just before I bought it I was going through the service history receipts & saw that there was an issue with one of the studs, said the lug was broken unable to remove wheel. Well, the dealer's mechanic then proceeded to try to chisel it off or something because it was totally all chewed up (fortunately no damage to wheel).
I ended up having to drill out the stud in order to get that lug off, to remove the wheel. It took a progression of drills working up from 1/8 to 1/2" & eventually the lug just fell off onto the drill bit. New stud & lug later, total cost about $2.50 (Big O tires simply gave me lug free when I tried to find match
Incidentally dealer who screwed up the lug, wanted $600 to replace the hub to repair it, which owner declined - all this denoted on the service receipt.
So, the wheel didn't fall off, but it did cause additional stress on the lug/stud due to only being on about half the threads.
Bottom line, you don't want to be driving a car like this with the lateral cornering forces it can create against only half threaded lug nuts.