Tire Size Calculations

[Jet Rootka]

The tire size numbers like
245 45 r16 can be understood this way....
The 16 is easy it is the tire diameter or the size of rim it will fit.
The 245 is in mm (metric) and is the width of the tire.
The 45 is the height factor and is a percentage of the width.
So to calculate the overall height, often needed for playing with various rim and tire modifications you will need to do some math...
245 (width in mm) x .45 (% of width shown on sidewall x 2 (for both above rim and under rim)=220.5mm plus your rim diameter will give you your overall wheel height.
This is most used when changing rim size and figuring best tire profile.
Ex... 225 60 r15 is the same overall height as 225 55 r16 if you remember to add 22.5mm or 1 inch due to rim increase.
An old school drag racer showed me this a while back and has
always worked for me even better than posted tire charts.

 

[General karthief]

Thats good to know, I found a tire measurement chart a few years ago when figuring what speedo gear I needed for the 355 gear in my axel and was amazed at the difference in tire heights from different tire brands of same size tire.

 

[Jet Rootka]

Thats good to know, I found a tire measurement chart a few years ago when figuring what speedo gear I needed for the 355 gear in my axel and was amazed at the difference in tire heights from different tire brands of same size tire.

I have noticed that too but... some appear rounder and others a flatter profile...,