1. Different Aspect Ratios: The first number in a tire size, which in this case is "205" for the 205 65R16 tire, represents the tire's width in millimeters. The second number, "65," represents the aspect ratio, which is the ratio of the tire's height (sidewall height) to its width. In this case, the aspect ratio is 65%, meaning the sidewall height is 65% of the tire's width.
65R15 tires only include the sidewall height indicator: "65R." However, if you assume the aspect ratio of 65% (just like the 205 65 R16), then the missing value you're looking for is the tire width. If this assumption is true, the tire width would be calculated by dividing 65% (or 0.65) by 65 and then multiplying by 15. This calculation results in a tire width of approximately 230.77 mm.
2. Potential Clearance Issues: The overall diameter of the 65R15 tire may differ from the 205 65R16 tire. This is because the aspect ratio (i.e., 65%) is applied to a different tire width (approximately 231 millimeters for 65R15, and 205 millimeters for 205 65R16). As a result, the height of the 65R15 tire may be significantly different, potentially resulting in clearance issues with your vehicle's fenders, suspension components, or brake calipers.
3. Speed Rating and Load Index Impact: Tires have speed ratings and load index values, which are part of their size designation. By neglecting the full size information of the 65R15 tire (e.g., "231/65R15"), you're assuming that the speed rating and load index values are exactly the same as your current tires. However, tire size changes can affect the vehicle's handling characteristics, braking performance, load-carrying capacity, and overall performance.
To ensure safety, compatibility, and optimal performance, it is highly recommended that you use tires with the exact size specification as recommended by your vehicle manufacturer or as outlined in your vehicle's owner's manual. If you have any doubts or uncertainties, it's always advisable to consult with a tire professional for expert guidance and recommendations.
