The tread pattern looked similar to mine, which are also H rated and the correct height for the speedo. Your's must be 15" since you still have the Campy's.
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.