While in Barcelona, Spain a few weeks ago, I bought a packet of Tres Cantos tomato seeds. The description on the packet says it is indeterminate and produces tomatoes between 180-200 grams (6 to 7 oz). It says med to large size, slightly flat, slightly ribbed skin. When I research further I find that Tres Cantos originated in the Tenerife area of the Canary Islands and can get really large. I am wondering if there might be two varieties of Tres Cantos, one more medium like mine and a larger one. Curious if anyone has grown this variety or knows if there are two possibilities. I will grow it this summer to see what I get and report back.
The company selling my seeds is called Rocalba.

I grew the Tres Cantos tomato in 2015. I think all the information about this tomato is in Tatiana's Tomatobase. As one of the few Spanish varieties whose seeds are sold commercially.
Vladimír

Yours don’t look somewhat flat or ribbed. Mine may actually be like yours leading me to believe there must be a couple of Tres Cantos varieties. Won’t know till I grow them.
I just checked Tatiana’s site and she describes them as being round and smooth. Her photos are mixed with hers matching that description. But the one submitted by Klaus-Peter Schurz is definitely flatter and more ribbed.
Rather confusing!