Does it burn more calories than cycling with good tyres? Because I had to ride my bike with a flat today as my pump doesn't work, and it felt like I was cycling on a road covered with glue!! It was so hard, my legs were burning!

Oh, my, if you biked on a flat tire, you may have ruined your tire frame... I'd take it into a cycle shop...

The reason it was difficult, and probably burned more calories, is because of the drag a flat tire will cause...

yes, it certainly burns slightly more calories, but it also breaks your tire frame!