I just replaced my tires and had the shop put new tubes in, just because I dont know if they have ever been changed. And while they were replacing the tires, it was just cheap insurance to have them do it at the same time. If you pay for mount and balance and then your tube has a slow leak, you have to replace the tubes anyway plus pay for mount and balance again. If you know the last time they were changed, you might wait. Just my 2 cents