What is the most weight you can have (in ounces) on a wheel and still be acceptable?
Good question! Remember that the lead weights we were used to seeing were heavier and more dense than steel, so more weight was accomplished with less metal. 1% of the total package weight can be used to balance. Don't forget that there are 16 ounces to a pound. So if your total wheel/tire combo is 50 pounds, up to 8 ounces in wheel weights is acceptable. For a 75 pound combo, up to 12 ounces are acceptable. Since a typical weight weighs 1/4 ounce, a 75 pound package could have up to 48 weights! (But you don't see 48 weights on a wheel very often.)
Why change from lead?
Lead was a very efficient means to balance a wheel, but with the environmental risks it "outweighed" the benefits. Think of the last time you bought a house and how thick the lead paint disclosure was. It has some negative side effects on the environment and our bodies. So the shift to steel was important!
Why move away from rim weights to stick-on?
The stick-on weight can be more precisely located and give a 3-dimensional balance a bit more precision. With more advanced road force balancers, placement can be more precise as well. Rim clamp weights risk damaging the bead and can cause leaks. Not to mention they damage your standard alloy wheel by scratching the epoxy/paint, resulting in the possibilty of road salt leaking into the scratches and damaging the wheel. The stick-on weights, when applied properly, are not going anywhere and are more aesthetically pleasing since they are hidden. All positives!
So when you are sporting around in your 2008 BMW and notice your Michelin tires are starting to vibrate and it's time for new, you'll understand the limits and guidelines for the wheel weights and will feel better about the how they're used during installation of your new tires!