Comparison Between a 235/80R/16 Trailer Tire and a 235/85R/16 Trailer Tire

Question:

what is the difference between a 235/80R/16 and a 235/85R/16

asked by: Ronnie

Helpful Expert Reply:

Good news! I can help you identify the difference between the 235/80R/16 and the 235/85R/16 trailer tires.

The difference between these two tire and wheel combos is overall diameter. This information is very helpful if you want to know if a particular spare tire cover will fit, or are trying to find out how much clearance you would have when switching to another tire/wheel combo.

The second number refers to the sidewall aspect ratio, this will help you find out the height of the sidewall from rim to tred. In this case it is 80% or 85% of the section width of the tire which is the first number.

The section width of a both tires in this case is 235mm or 23.5cm, to convert into inches we will divide this number by 2.54, because 1 inch is about equal to 2.54 centimeters; 23.5 / 2.54 = 9.251 inches. So 80% of 9.251 = 7.40 and 85% of 9.251 is = 7.86.

To find the total diameter of the tire and wheel combo we will need the third number which is the height of the wheel and in this case it is 16 inches. Then we need to plug this into our formula.

Formula:
Total Diameter = (Section Height x 2) + Wheel Diameter

So the overall diameter of the 235/80R/16 (7.40x2+16) tire will be 30.8 inches, and the overall diameter of the 235/85R/16 tire will be 31.72 inches.

I have linked you to a Help Article on determining tire and wheel diameter for your convenience.