Depends how long your frontage is. 75 feet apart would be ideal but planting them closer will give you denser shade. I hope they are planting caliber sized trees because it will bo sometime, maybe your grandchildren before they look like the trees they are replacing.

Here is a link that might be useful: Propagating Perennials

old1800home: Autumn Blaze maples grow fast: Height: 50' - 60'; Spread: 30' - 40' In an earlier post about spacing Autumn Blaze maples, it was suggested that the trees be spaced about 25' apart. (see link below)

bullthistle: The OP's question was about how to space Autumn Blaze maples. You recommended 75 feet apart, although the trees grow about 30 feet wide.

At the bottom of your answer you added a link to your blog, "Propagating Perennials." I went to the blog and searched for information about maples - the search revealed nothing.

I'm confused. When people add "a link that might be useful," that link provides additional information about the subject. Why do you add links to your blog when it does not include information that would help the person who asked the question?

Here is a link that might be useful: Spacing Autumn Blaze Maples

Careful! Thistles can be prickly.

For additional discussion search by cultivar name 'Jeffersred'. This should give a pretty well targeted list of hits.

Here is a link that might be useful: United States Patent: PP04864