Running MT ET Street DR's 295/55-R15 (28" tall) on 9" rim.
Diameter - 27.9"
Section width - 12.0" on a 9.5" rim (about 11.5" on 9" rim, 10.8" on a 8 " rim)
Tread width - 10.8
Approved rims - 8-10.5
from MT rep on yellowbullet.com...
The P295/55R15 is a replacement for our 28.0/10.5-15 ET Drag and the 28X12.50-15LT ET Street. Race tires are designated by tread width, street tires use section width.
If you are running the 28X11.50-15LT ET Street (# 3754), and can't go any wider, you'll wnat to use the P275/60R15 ET Street Radial (#3754R)
Last pic is next to my 255/50-R16's on stock 8" rims.