It will depend on whether it needs to be patched or just repaired. Turn them inside out, pin and then sew with heavy duty thread and needle for denim. If you need to patch, cut a piece of denim slightly larger than the tear and place on the inside of the jeans. Sew the patch in place.
Where are the jeans ripped? On a seam, by the zip, or in the body of the fabric?
When sewing, use a jeans denim sewing machine needle.
The shaft is designed to perforated dense denim easily, which will help prevent needle breakage and bunched threads.
Wow never knew that there was a special needle for jeans and denim, thank you.