If the tire with is P175, that's likely to be 0.175 meters, 17.5cm. I doubt your tire is 1.75 meters wide.

The number 175 in a tire size (e.g. 175/55R16) is the width of the tread of the tire in millimeters (mm). A tire which has a size of 205 as the first number is 205mm wide and wider than the 175mm tire. The second number (55 in this example) is the value of the height of the sidewall of the tire. It is represented as a ratio of the tire width and referred to as series. For the 175mm width tire a 55 series tire is higher than a 45 series tire. The last number represents the rim size of the tire. It is measured in inches. In this example it is a 16 inch rim. So, for a tire size of 175/55R16, this tire is 175mm wide, has a 55 series sidewall height and mounts to a 16 inch rim.