I choke just typing the words, but JC Whitney has them:
http://www.jcwhitney.com/wheel-covers-chrome-plated-factory- style-wire-spoke/p2003983.jcwx#prodDetailTabPanel
You can also try the ebay route, like this auction:
http://cgi.ebay.com/ebaymotors/New-Set-15-Inch-Wire-Spoke-Hu b-Cap-Rim-Wheel-Covers-/360368162327?pt=Motors_Car_Truck_Par ts_Accessories&hash=item53e79dc617
I imagine mainstream autoparts stores like AutoZone, PepBoys and the like will have them in their stores.
The problem will not be finding them, the problem will be matching what you have OR finding a set of five, if you want to use one on your spare tire.
PMOSSBERG40707.6652083333
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)