It all depends on what you are going for.
I need to improve on cardio in general so I will do a 10-15 minute session of either sled pulling, tire flipping, or a heavy wheel barrow. I get my heart rate jacked and then walk around until it comes down a bit and do it all over again.
If the tire is truly 800lbs then most people wont be able to flip it. At nationals we had a 850+lb tire and a lot of the Strongmen couldnt get it off the ground once. I got 3 that day and was completely spent.
As far as other implements of cardiovascular torture, I would get some sand bags and a large duffle bag so you can load them all in together and change the weight 50lbs at a time. Also, any object (stone, concrete block, anvil...) that can be used in a front carry. When the weight of the object is crushing your chest, your cardio has to be top notch because you arent getting as much volume in each breath (as well as you are carrying a big ass weight).
Have fun and let us know how it goes.