[Wavery]

The other thing that is a good idea is to replace the spare every time that you replace your tires. Unused tires are more susceptible to rot than the tires on the ground. Visual inspection is not enough to detect cracks in the sidewall of the spare because it is not in use. The first time that you mount your spare and drive for a few miles, the cracking may become quite evident. Just because the surface is not cracked, doesn't mean that the tire isn't rotting under the surface. It is even common for an old trailer spare (that looks fine before mounting) to fail in the 1st few miles.

When replacing tires or stems, always request steel valve stems. They cost a little more but rubber valve stem failure is the most common cause of trailer tire failure.