Welcome aboard!
165R/15 is the standard size radials for a VW Type 1 (Beetle).
Tirerack usually has them (although I just checked and came up empty).
JBugs http://www.jbugs.com/store/merchant.mvc?Screen=CTGY&Cate gory_Code=VWT1
California Import Parts has ’em. Be careful, prices are quoted in Canadian Dollars http://www.cip1.ca/SearchResults.asp?Cat=1266
DealParts in Costa Mesa California for $60 a piece http://www.dealparts.com/product/10-4022-0.html
Vee Dub Parts (a little pricey) http://www.vwparts.net/TIRE.html
I would not put bias ply tires on. I had bias ply tires on when I first built my TD. It wanted to follow every little groove it could find on the highway. Ride and handling are far superior with radials.
PMOSSBERG39848.6774074074
Paul Mossberg
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica Roadster
If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)