There are lots of opinions about wheel weight alloy so far as content, but rest assured, the wheel weight metal which has been produced for the last 20 years at least has not changed, and isn't likely to, as it is the lowest cost alloy possible to make that will produce suitable wheel weights. I am talking here of car type wheel weights with steel clips. The tape on weights are commercial pure lead, which means very soft but not laboratory pure.
Current WW alloy is real close to 2% antimony, perhaps a half % tin a trace of arsenic and the rest lead, and I suspect the lead part varies slightly as silver is in every known lead mine in the world, but isn't worth smelting out, or wasn't a few years ago when I was given this information about lead mines by a brother who was into precious metals at the time. But silver was only $6 per oz then.
A little tin will help castibility of wheel weight metal, but don't add more than about 2% max. 1% will be adequate to get very good castibility and my preferred tin source is no lead plumbing solder which is labeled 'tin bearing'. I only add 2 or 3 inches of the 1/8 inch wire to a 20 pound pot, which is almost nothing in percentage, but aids casting quite a bit. I'm too cheap to add more because I see no difference in performance, except for soft hunting bullets, and information on that is covered in detail in my book.
Don't use tin lead mixes except for black powder and then only if using bullets with under size noses which must bump up via chamber pressure to get accuracy.
