Notes on the 3D Model and optimization for in-game use:
Good start, but before you go unwrap the UVs and go through all that hassle:
Remove the treads, they'll be handled by a texture, same goes for the wheels. Remember that polycount is an issue, it always is. Where a minute detail could be handled by something else, let it. Otherwise for high-polygonned pre rendered graphics you'd want to render the wheels.
If you might, you could consider taking a look at these as reference on the US Armies MCS system.
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Infantry Carrier:
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Israeli Merkava Mark IV
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The People's Army Type 99 0 (China)
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Non line of sight mobile cannon:
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I hope these help you out in your quest. Whenever I have to make up something new and futuristic, I always try to draft it out first, so I can work out all my bugs, and then I work from that.
You may consider removing or adding new features, such as a new type of track system battle hardened in the Chinese civil war, of 2050something or even a new system based on gatteling railguns, which I've seen drawings of, yikes!