Do you feel confused when you read tire sizes?
You will not after today!
I have trained lots of newbies in my previous employment experience. Let me help you!
When I have started to work on the tire manufacturer, I was completely crushed under the tons of tire sizes. I was afraid and don’t know what to do.
At that time, I have decided to use my favorite method.
Divide and conquer!
Alright, first of I would like to define our elements. Let’s divide it to three.
285: This elements defines the width of the tire. Unit : Milimeter
75: This element defines sidewall height. But, it is on ratio form. If you want to real height of sidewall, you have to multipley this ratio with tire width (285×0.75=213.75). Unit : Milimeter
R17: R means ‘Radial Construction’. So, the number come after the R is the rim size. Unit : Inch
Now, it is time to make some calculation. Continue below the see our, height calculations.
We’ve prepared the above guide for you. We think that it will help you with our calculations.
At first look, the only difference between these two sizes is the middle element. It is ’70’ and ’75’. Yet, this ratio has a direct impact on tire height. Let’s calculate it together.
Height = (Width x Ratio)x2/25.4(1inch=25.4mm) + Rim Size
In other words,
Height = (First Element x Second Element)x2/25.4 + Third Element
‘x2’ highlighted with red caused by two sides of the rim.
Height calculation :
Height = (285×0.75)x2/25.4 + 17 = 33,83 inches
Height calculation :
Height = (275×0,70)x2/25.4 + 17 = 32.15 inches
As you see, 5 points difference in a ratio equals 1.7 inches difference in tire height.
Please note that this calculation only works for the same patterns. Different tread depths can change tire height.
Where to Use It?
- If you wanna increase your vehicle elevation, you can use the tire with higher ratio size
- If the tire is too big and you don’t want to use a lift kit, you can use lower ratio size
These are the basics of tire size comparison. I hope the article was helpful!
If you have any further questions or any other information content; please leave it in to comment section. I would love to help!