The diameter of the wheel is calculated by a simple formula: the diameter of the disk to fold double-high profile tires. This method of calculation is used for cars only.
Measure the diameter of the wheel in the usual way - with a tape measure. Each of the parameters above described formula measure separately. Then, the resulting values translate to inches (because it is in them and calculated diameter of a car wheel). You can do it like this: the number you divide by 2.54. Next, add up all the values that you got when measuring in inches. This will be the diameter of your wheel.
You can simplify mathematical calculations and use a more simple formula. To do this you need to the number denoting the width of the rim, add 20% and you just get the width of the entire wheel. In cases when the tire is narrow, the difference between the total wheel width and the width of the disc will be 15%.
Greatly increase the overall diameter of the wheel experts recommend a maximum of a couple of inches. After all, the wheel that far exceeds the norm in size, will be scraping along on the rapids of the vehicle and prevent movement. Besides, he has almost no coupling with the road.
If you want to increase the diameter of the disk, choose tires a little small. However, with the reduction in the width of the tires also do not get carried away, otherwise the bus will not sustain its load. Therefore, try as much as possible to strike a balance between the overall diameterof th wheel and drive.
Of great importance in the automotive wheel has such a value as the diameter of the rim. Remember, the settings wheel on this item can range from 10 to 23 inches. Small figures usually inherent in motorcycles and mopeds. Used for large powerful vehicles.
If you still doubt their methods or calculations, refer to the experts. To do this, visit any automotive technical center. There you all will measure with millimeter precision.