Then usable tread depth is compared to remaining tread depth in order to calculate tread wear percentages. For example, a tire that started with 10/32 of original tread depth and has worn off 4/32 (down to 6/32 of remaining tread depth) is 50% worn.
1 If you know the census tract number: Use the IRS list of 2014 Qualified Census Tracts by county. 2  If you have a street address: Visit HUD's interactive QCT Map and enter the property address to view what Census Tract the property is located.
Watershed hydrologic units (HU) are generally subdivided into 5 to 15 units. The average size of an 8-digit sub-basin hydrologic unit is about 450,000 acres. The typical 10-digit watershed size is 40,000 to 250,000 acres, while the typical 12-digit subwatershed is 10,000 to 40,000 acres. 8- and 10-digit watersheds can be derived from 12-digit watershed shapefiles.