Are you talking about the monster truck tire flips? There's a highschool right near my girlfriend's place. They have a 400 pound tire there. I end my workouts with 8 sets of 5 tire flips and a 100 yard sprint. I love tire flips. They engage all of the large muscles.
What were your times like? I didn't have access to a pullup bar or a a box for jumps so I substituted the pullups with burpees and the box jumps with 100 mountain climbers. My time was 11:26. I tend to do about 3 days of circuit training a week as well. I'm going to use this as a benchmark for progress.
*Edit- The rubber track...duh!!
I like the beach. If you have one near you, it's both more challenging and better for your joints!