Home treadmills are very useful for keeping yourself in shape without the need to travel or own a gym membership. Treadmills have some drawbacks because they are typically heavy and take up a lot of space. They vibrate when they are in motion, and the combination of weight and movement often damages tiles floors. Placing a mat or buffer between the floor and treadmill prevents this problem.
A rubber mat is useful because it pads the floor from the treadmill's weight while also providing enough grip on the floor to prevent the treadmill from sliding on the tile. Rubber mats often are used in gyms for this reason. Rubber mats absorb moisture, which is useful if you build up a sweat while the treadmill is in use. Rubber mats have varying thickness, so you have options to choose from when picking a mat to fit your needs.
Plastic mats are not as absorbent as rubber, but they are resistant to moisture exposure. While rubber sometimes absorbs water like a sponge and can suffer from mold and bacteria as a result, moisture pools onto plastic so it can be quickly cleaned with a towel whenever your workout is finished. Plastic could slide on tile, depending on the specific mat and the type of treadmill you have on top of it. Plastic mats usually are used for preventing floor damage from computer chairs that have wheels on them, but larger varieties can be used under treadmills and the clear coloring makes them less noticeable.
Cloth mats are more decorative in nature and therefore a more attractive option for you to consider. The downside is they are more likely to slide on a tile floor and therefore don't typically provide the same level of protection as a plastic or rubber mat. Cloth also absorbs moisture, so heavy sweat or spilled water while running could cause mold problems if the cloth is not dried. Cloth mats are not an ideal solution, but they provide more protection for your tile floor than having nothing under the treadmill at all.
Carpeting functions much like the cloth mat without the risk of sliding because it covers the entire floor. The weight of the treadmill causes deep indentations in the carpeting that likely become permanent, so you should place a mat over the carpeting if you want to keep it looking like new. The carpet is effective at preventing scratching to the floor underneath, and the treadmill is not likely to slide on a carpeted surface, especially once the indentations have formed because they help to hold the feet of the treadmill in place. Carpeting also provides a decorative element because there are various styles and colors available.