It is never a good idea to leave your bowling balls in the car over night, if you can help it. Take them to a warmer enviroment, put them to bed, cover them up nice and tight and kiss them good night.
In the morning, if you have to put them in your car, make sure you bundle up your little ones. Add an extra layer of clothes in the winter, maybe even a scarf and a hat.
Other than that yes, if they are left in a cold trunk, and then you take them in, the core could separate as the ball(s) are smashing into the pins. And yes they will crack.
Be gentle to your balls
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Dale Williams
Columbia 300 Utah Amateur Staff