Hmmmm....I have rarely had split tomatoes but I know Dad did during hot, dry summers. I have since moved the tomatoes from the south side of the house to the east side of a three foot fence. They seem to maintain the moisture there better. Watering deep and often, mulching, and feeding often. IMO, this is the only way to avoid splitting. I put gallon ice cream pails over my transplants when I set them out. This helps the water soak in slower and goes more directly to the roots. I water every night with a bucket or open hose, unless it is raining heavy, and fertilize, at least, every two weeks.

Ginny

Fluctuation in growing condition, like hot and cool, water etc... that's what I was reading up. Deep mulching might help.
Another thought I have is,.. planting them too early, especially when you have little tomatoes already on the plant and planting outside, the skin or tomatoes are too old and can't stretch as good as even grown fruits from beginning, [flower] then, eventually burst.

Well I did a whole bunch of pruning today and it looks like the newer tomatoes are doing better for filling out without splitting. Now to get them ripe!