First off, pictures:
From L-to-R, a less ripe (and less strangely textured) tomato, and a ripe one with full-fledged spiral on top.
The inside of a halved tomato with the same problem. The top was tough to cut (for a tomato - and, yes, I used my serrated knife).
We also have cherry tomatoes in our garden, and none of them seem to have this problem. The apartment's owner and tomato caretaker until the end of August (we are subletting) warned us that if they sat in the sun too long they would split, but he never mentioned this.
We are in Brooklyn, NY; we have had plenty of rain lately, alternating with plenty of sunshine. The weather has been above 65F (but never above about 82F) during the day since we moved here. As I said, we are not the original growers so I have no information on what products/fertilizers and what have you were used.
Concentric splitting is seen as circles around the stem that usually scar over and there's a genetic association with certain varieties.
Radial splitting is seen as splits that radiate outwards from the stem and they also have a genetic association with certain varieties.
So both of the above are consedered perfectly normal for many varieties. And unless there's heavy rains or overirrigation which opens up the scarred splits when rotting can ensue, it's not a problem/
Horizontal splitting is any splitting that occurs elsewhere on the fruits and is due to uptake of too much water when the fruits are at the mature stage since the skin can't expand to accommodate the increased water.
posted by weapons-grade pandemonium at 12:31 AM on September 26, 2006 [1 favorite]