I don’t seek out lead sources anymore because truth to tell, I’ve got more lead than I’m ever likely to use at my age. If I were starting out today looking for a supply of lead alloy to work with, wheel weights would be low on my search list for the reasons mentioned above. I do have about 100-150 lb of ingots of old wheel weights gathered and rendered at least 25-30 years ago by my late father, so I trust them to be good old fashioned COWWs and am confident to use them accordingly.
My advice if you want wheel weights, look for an old fart who has been casting for decades and has decided to get rid of his supply because he won’t use it now.
Froggie