Picked up some unusual motorcycle wheel weights that look to be pure Tin.

[jrebs]

Hi folks,

There's a local motorcycle shop that is nice enough to supply me with their scrap wheel weights every now and again when the tub fills up (very, very low volume compared to what most people consider a viable lead source - but every bit helps and they're nice dudes to chat with).

Today I went and took the pail which was probably only about 5lbs worth, and most of it soft stick-ons, but for the first time ever, I encountered these conical/cylindrical shaped wheel weights that appear to be used for installation on spoked motorcycle wheels. I've never seen this before and, interestingly, they are marked on top "20 Sn" and "30 Sn" which I presume means the weight in grams and the composition is Tin.

Does anyone here have experience with these and/or can anyone confirm whether these would be made of pure Sn or wether I should expect it to be an alloy of some sort?

Photo included. Thanks in advance for feedback.

[jimgun]

I picked up a bunch of these sometime in the past, so I will be watching to see what the experts say also. jim

[I'll Make Mine]

I'd be amazed if those were actually pure tin (or even high tin content like lead free solder); both on cost consideration and because the weight would be roughly 50% larger volume for the same mass than lead. Most likely the Sn is a manufacturer mark of some kind, and the weights are the usual "whatever was handy" lead alloy (3% antimony and trace to 0.5% tin, usually).

One way to check is to compare water displacement of the 30 gram weight against a 30 gram known lead weight; if they're close to the same volume, they're close to the same alloy.

BTW, those probably aren't for motorcycle wheels; more likely they were for wire wheels on vintage sports cars. Modern motorcycles use a tubeless tire system almost identical to car tires from the past thirty-plus years, and use stick-on weights applied inside the rims. I haven't seen a new wire wheel on a motorcycle since the 1980s (maybe longer than that; my 1979 CM400T had stamped steel wheels).

[dbosman]

Cast a bullet and weigh it.

[JIMinPHX]

That style of WW is still used on spoked motorcycle wheels, but I've never seen SN in them before. I too am waiting for more information.

[jrebs]

When I can find time to do it, I will slowly heat up my smelting pot with one of these mystery wheel weights and a piece of soft lead sitting in the same spot on the floor of the pot. If the item is tin or contains a lot of it, I believe it should melt much sooner than the lead. If they are roughly the same alloy they should melt at roughly the same time.

[Bulldogger]

The few I have found were Zinc

[jrebs]

Well, the melting test will definitely answer the questions. If it melts before lead it's tin(ish), if the lead melts first, it's probably zinc. Based on a test with tin snips, these seem way too soft to be zinc. I'm not sure of Sn hardness, but these were quite easy to cut into, so it seems quite possible that they are lead or primarily lead.

[Jailer]

Probably are tin, you can still buy them.

http://www.amazon.com/Supply-Weights.../dp/B0041CG0P2

[I'll Make Mine]

Tin is harder than pure lead, but not as hard as zinc. If they cut easily with wire cutters or snips, they're not zinc. Do they get a glossy, polished looking surface where you scrape, and can they be scratched with a fingernail? If so, they're lead; of too hard for fingernail scratching, they might be tin (and I can see tin being used for these in lead-free zones, it's soft enough to crimp onto the spoke like lead, where zinc is too hard for that).