I'm planning on growing in tires this season, on a budget. I'll be bringing in some compost, and growing mostly vegetables (tomatoes, cucumber, pepper, beans, melons, carrots...). Anyways, I'm planning on growing the tomatoes, cucumbers and melons vertically. As well as the beans. I was planning on something like this...

Having metal fence posts (t-post) staked into the ground at *intervals. I want to have a *metal chain going across the tops, from one to the next, and either rope running down to wrap around the plants, or wire run from pole to pole.

The rows of tires would sit in between the poles, perhaps offset.

Questions..

1) How far apart can the fence posts be from each other and still be structurally sound?

2) Is a metal chain ideal for going across the top? It sounds strong.. Any problems that may arise?

3) Would you recommend running wire across, or down from the top to support the plants as they grow upward?

How does the entire structure prevent itself from collapsing inward under the immense weight? Any other ideas for the tomatoes, cucumbers and melons, growing vertically?