the wheel skin is 0.75mm thick, and was specifically designed to a goal of 10 to 20 km with the smallest weight possible: the rover mass is 899kg, the launch vehicle totals was 531000kg - by reversing the payload fraction one can see that for every gram of rover one needs more than half kilo of rocket to get it to mars, so there's that - you can get outside of your launch weight real fast.

this article has all the answers you're looking for:

http://www.planetary.org/blogs/emily-lakdawalla/2014/0819063...

short story - the wheel were tested to specification against expected rocks etc but once on the boogie suspension the front wheel had to support weight plus the force of the other wheel pushing, so there's where the extra punctures come from, this is what force was not accounted correctly.

It's been four years, the wear could be as much a function of time as of travel. Car tires on earth dry out, crack and disintegrate over time.

The skin is "about half as thick as a U.S. dime". A car tire that thin wouldn't last a 10 mile drive.

The tires are extremely thin to save on weight. Take a look at a dime and think half of that!