Any reason not to put your tefilin inside your car's spare tire when driving?

Question

For cars that store their spare tire in a well inside the trunk, that seems like a good place to put my tefilin while driving -- it takes up no extra space (if they fit in the middle of the tire), keeps them from rolling around, keeps them covered (of course you risk forgetting them there!).

Assuming they're not getting dirty or greasy -- any reason (practical or halachic) not to do so? Yes they might end up smelling rubbery ...

Answer 1

Be very careful that you don't forget them back there, especially on a hot day. I know from unfortunate experience that prolonged storage in a hot car is very detrimental to the health of the straps, at least.

Answer 2

Tefillin should not be left in the car, particularly on a hot day. If you have no choice then put them in a freezer bag or insulated bag.

The parshios are at greater risk than the retzuos. Also why not keep them in the car when driving. At least the temperature is regulated by a/c or heat. I'd assume the inside of the spare tire is under the hood or outside of the car, where it can get hot or cold.