The gritty texture that pears sometimes have comes from tough cells called scleroids. Most of the scleroids are under the skin, so peeling the pears before dehydrating them results in a better texture.
Peel whole pears with a vegetable peeler. Cut into quarters and slice out the cores and stems. Cut into 1/2-inch slices.
Note: other fruits, such as apples, do not have scleroid cells and do not need to be peeled before drying.