My tire is 26.5". I ordered size 30-32 and it seems to fit perfectly. The material on the back is a soft fabric that hugs the hoop and is long enough to cover the bottom of the hoop. I don't know how a smaller casing would possibly fit my tire. I didn't give it 5 stars because there is no strap on the back to secure the bottom of the tire from gusts of wind.
Yokohama Ice Guard IG50 215/50 R17 99Q winter
36 Review
Nokian Tires Hakka Green 3 205/55 R16 94H summer
37 Review
Nokian Tires Nordman RS2 SUV 225/60 R18 104R winter
32 Review
4WD ORCISH Recovery Traction Boards Tracks Tire Ladder For Sand Snow Mud - Set Of 2 (2Nd Gen Bag + Mounting Pins, Black)
39 Review