Depends what is at the bottom of the hill. I mow with a ZTR on hills where the bottom is smooth and grassy. I have slid down a hill in the rough that caused the ZTR to roll over when it hit a rut at the bottom of the hill. I also have a hill with a vinyl fence at the bottom. I removed a section, so that once I start sliding I can aim for the hole to avoid wedging into the fence. I have another ditch with a woven wire fence at the bottom. I just don't mow that anymore. I tore up too much equipment sliding into it.