"Homemade" canned goods? That's an interesting question.
When it comes to commercially canned foods, a number of factors should be considered. For example, where was the food stored? Was it in a cool, dark place? Or was it subjected to temperature/humidity fluctuations?
Commercially canned foods should be used, in most cases, within 24 months from the "use by" date.
Having said that, I would hesitate to use your canned tomatoes.
With any luck, MichaelinFTW will weigh in on this subject. In that case, I defer to Michael...
Michael, you're on.