Since the silver mercury and the silver roosevelt were the same diameter and weight, they would have to have been the same thickness. In 65 the size and thickness remained the same, but since the clad composition has a lower specific gravity, the weight is lower.
Well, the thickness of a clad dime is more variable than an old silver dime. Weight is determined by the thickness (and compo- sition) of the strip from which the planchet is punched. This thickness has not changed for dimes since the 1850's if mem- ory serves. (it decreased 1% for quarters in 1999). Thickness of a coin is determined primarily by design and strik- ing characteristics but also by planchet thickness and upset- ting characteristics. Clad dimes can be very thin where they are struck with low designs and lightly upset. (rolled between two rollers to reduce diameter of planchet) Such coins tend to have low rims like the 1999 issues. Other dates can be much thicker. Proof dimes can be 10% thicker on average than BU examples. Even within the same date there can be substantial variation. Generally poor strikes mean thinner coins but even this isn't a given I believe. Most modern coins have significant changes from year to year and some of these changes do result in thickness variability. Clads aren't made to as exacting standards as pre-1950 coins and this increases variability as well. Quality has been improv- ing in the past decade and much of this has been at the expense of relief (which also affects thickness).
It varies on the same coin. I just checked a 2008-P and the rim thickness went up to 1.42 mm at the top to 1.20 mm at the bottom.
It will vary slightly (<>10%) but be about the same It will vary slightly (<>?10%) but be about the same.
