I have radials front and back on my Vegas. No issues with handling. I myself am looking to upgrade to a fat front tire like being offered by Vicbaggers.
https://www.vicbaggers.com/product-page/21-fat-tire-kit-indian-victory-harley-davidson
https://www.vicbaggers.com/product-page/21-fat-tire-kit-indian-victory-harley-davidson