23540-R18 tires are 1.56 inches (39.5 mm) smaller in diameter than 325/35-R18 tires and the speedometer difference is 5.7%. Thecomparison charts above represent detailed calculations of the difference in size between 275/65r18 and 35/12.50r18 tires. The resulting calculations of tire diameter and width, sidewall height, circumference and rim diameter are provided in the form of comparison table and visual graphics to better convey the difference between 275/65r18 3312.5-R20 tires are 1.11 inches (28.22 mm) larger in diameter than 275/55-R20 tires and the speedometer difference is 3.4%. Tyresize explained Tyre dimensions. Width: The section width of your tyre in millimetres, from the inner sidewall to the outer sidewall. Example: 195mm. Aspect Ratio: The height of your tyre from the base of the tread to the rim, as a percentage of the tread width. Low profile tyres have smaller aspect ratios. Example: The height of this tyre is 65% of its width. 30570/18 is 34.8X12X18, but I would not expect to see that 34.8 as you will usually get something less (so maybe 34). Here is how you do the conversion for you reference: 305mm is the tire width, converted to inches this is 12.00787 inches. To get the height, take 70% of 12 (this is sidewall height) X 2 (above and below the rim) + rim, so WheelWidth Minimum Tire Width Ideal Tire Width Maximum Tire Width; 5.0 Inch: 155mm: 165 or 175mm: 185mm: 5.5 Inch: 165mm: 175 or 185mm: 195mm: 6.0 Inch: 175mm: 185 or 195mm Itis 265 mm wide = 10.43 inches (approx). What is the difference between 235 65 R17 and 245 70 r18? 235 / 65 / R17 is ( 29 inches in diameter and the tire section width is 9.3 inches ) 245 / 70 / R18 is ( 31.5 inches in 30565-R18 tires are 0.41 inches (10.54 mm) smaller in diameter than 34/12.5-R18 tires and the speedometer difference is 1.2%. Tiresizes. 18 inch tires. 35-12.5r18 tires. Did you find what. you were looking for? Find the largest selection of 35/12.5R18 tires you need with SimpleTire. Look for the size you Janu. 775 Views 0. 31X12.5R16 tires are 31.0″ tall, have a section width of 12.5″, and fit wheels with a diameter of 16. The circumference is 97.3″ that translates into 651 revolutions per mile. As a rule, they can be mounted on the wheels with 16″ rim width. In the metric system, the equivalent tire size is 318/60/R16. qsMg.