My niece brought in a Guinness Book Of World Records the other night and I flipped through it. It was the 2008 version and so Radar was listed as the tallest horse in the world (don't know if he still holds the record or not). This got me thinking...
What is the tallest horse you have been around?
Mine would be a thoroughbred named Lurch. He was abandoned at a facility and had all sorts of health problems, including a large ball on his elbow that he was due for surgery for before he died. Lurch measured 18.1 at the withers and I do believe that they were trying to get him into Guinness as tallest TB. I'm unsure of whether he had a lip tattoo but I think his lack of papers might have kept him from the title.
Here is Lurch (RIP) about a year before he passed. He was 18.1 Hands. The girl ontop of him is somewhere around 5'10'', I believe. He was ridden in light dressage to keep any kind of muscle on the poor guy.