Eventually, wear and tear means you need to replace the property. By that time the gov has provided you some assistance to do so.
This and like any property you use for business it's considered outside your normal 'enjoyment use'. When I was using my car for my side business, I could write off all 'side business' related use. However, my normal commute to my regular job; going out to clubs, shopping, just cruising, etc and the like were not write offs.
With a true rental, eventually the tenants will wear out the place. You didn't get the usage of it. So although you must pay tax on the profits, you are also entitled to a break in keeping it livable so good old Uncle Sam can get those taxes. He wants to help you help him
Don't stop at the rental itself though. Think about your computer, phone, printing, stamps, supplies, even utilities you used to support that rental. These costs are often trivial by themselves, but together can add up to a nice buck. The government will let you recapture that if you are willing to do the work and keep those records.
I have found though keeping the proper documentation from day 1 is a lot easier (and more profitable) than trying to reinvent it on tax day.