The GTS model questions.

The early GTS Panteras (both European and North American versions) were equipped with the same tires as the non-GTS versions. The North American "GTS" Panteras were a one year - 1974 - model. They were fitted with wheel well flare extensions for looks, not by necessity. They were only shod with C60 & H60 Goodyear Arriva tires mounted on the standard 15x7 & 15x8 wheels, same as the Pantera L.

The 15x10 wheels were developed in 1973, but I can't say with certainty when they were first fitted to the European GTS, my "guess" would be 1974. There was a period of two or three years however when the European GTS were equipped with the wider wheels, but shod with C60 & H60 Goodyear Arriva tires.

The technology to produce wide/low profile radial tires was developed by Pirelli in 1974. The Pirelli P7 tires were developed in 1975 at the request of Lancia for the "high output" version (275 - 320 bhp) of their Stratos rally car ... the car needed something better than the 205/70R14 tires of the standard model (which made 190 bhp). The first production car to be fitted with the P7 tires (besides the Lancia Stratos) was the first Porsche 911 turbo (260 bhp in 1975). I don't think De Tomaso began using them until 1976 or perhaps 1977, as the P7 tires became available in a wider range of sizes.

New information for me George, so thats why I don't have 10 inch wheels my car was a year too early for them!
Wonderful to read, and learn rather than just guess and not know.
In my 3840 file I have so many snippets of information of yours that I have printed out.
I think it must be time for a book, Please.
thank you for your help. Peter.

I was looking through a few books earlier today regarding your question, I found one that said De Tomaso began installing the 15x10 wheels on the GTS in 1976. One thing I know for sure, I've seen many pictures in brochures, books, etc. of GTS Panteras with the wider wheels and Arriva tires.