Riding on streets requires different tires than riding off road on dirt and rocks. And possibly a different type of bike. A road bike will not do well on dirt and rocks even with different tires. Sounds like a mtn bike or a low end cyclocross bike is what you want. You can ride on the road with off road tires but the ride can be noisy and uncomfortable.
Now, read this -->
http://www.intownbicycles.com/how-to...oose-a-bicycle
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The Lord is merciful and gracious, slow to anger and abounding in steadfast love. - Psalm 103:8
I am a cyclist. I am not the fastest or the fittest. But I will get to where I'm going with a smile on my face.