Lawnmowers that are good for hills are specifically manufactured for the task and can mow hills with an angle of up to 15 degrees. These mowers have unusually good traction and accept tires that are rated for hills.
The best mowers have a 2003 ANSI B71.1 label awarded by the U.S. Consumer Product Safety Commission. Mowers that are good for slopes are front-steering as opposed to having a zero-turn-radius. ZTR mowers tend to flip over on slopes, especially if they are driven too fast. A riding mower with a deck of between 42 and 54 inches is also good for mowing steep slopes. Mowers used for steep slopes should also not be used with attachments such as rear bags or lawn vacs.