If the tire diameter is not given, section widths ending in zero (e.g., 7.00 or 10.50) indicate the aspect ratio of 92%, while section widths not ending in zero (e.g., 7.05 or 10.55) indicate the aspect ratio of 82%. These aspect ratios often vary from today's tire manufacturer specification. Construction of the fabric of the tire: B: bias belt D: diagonal R: radial 2-digit number: Diameter in inches of the wheel rim that this tire is designed to fit.