Tafsir Ibn Kathir , you can find digital PDF versions and physical sets from several reliable sources. The complete Tamil translation is typically published in a 10-volume set Free PDF Downloads
While not strictly a PDF, many apps (e.g., "Tamil Quran with Tafsir Ibn Kathir" on Google Play) export pages as PDFs. This is a trustworthy route because app developers are usually bound by religious accountability. Tafsir Ibn Kathir In Tamil Pdf