NASA's Curiosity rover is equipped with tough aluminum wheels, but they're not getting off easy on Mars. The red planet's rocky landscape continues to take a toll on the rover, as new images of wheel damage show.

The rover used the Mars Hand Lens Imager (MAHLI) camera on the the end of its robotic arm to take a close look at its wheels on July 7. This is pretty much the rover equivalent of inspecting the bottom of your boots after going for a rocky hike.

The wheels are dented and pockmarked from traversing rough ground. What's most concerning are the many cracks and outright holes visible across the treads.

While the damage looks scary, the wheels are actually doing a pretty good job of hanging in there.

"Although the wheels have developed some holes, the testing and modeling that have been done since early 2014 indicate that Curiosity can still travel a number of kilometers on these wheels," Curiosity team member Roger Craig Wiens wrote in a mission update.

The rover has traveled 12.99 miles (20.91 kilometers) since reaching Mars in 2012, so the wheels should still be serviceable for quite some time.

NASA checks in on Curiosity's wheels regularly. A view from early this year looked just as startling as the new images. The damage won't get better, but Curiosity's team has devised clever ways to work through it, including adjusting the speed of the rover's wheels to reduce pressure from rocks.

With Opportunity now defunct, Curiosity is NASA's only remaining Mars rover. At least until the new Mars 2020 rover arrives.