You must have heard many a times when some of your friend would say that my car has 14 inch rims or 15 inch rims. And most of us also know what is the rim size is the size of the rim of our car. However most of us dont know what is accounted when we say 14 inches. Rim size is the slang for Rim diameter. So whenever you go out to buy an Alloy wheel if you mention that you are looking for 14 inches rims. You actually mean that you want Alloy wheel with the Outer rim diameter of 14 inches.
You must have also noticed that when we are changing our tyres the shopkeeper would ask us the rim size. This is required as tyre with rim size 14 would only fit alloy wheels with rim diameter 14. So far so clear? Lets take it further
When you read a tyre it says for ex. 185/60R15. Here the R stands for Radial and not Rim size. The number after the R stands for the inner diameter of the tyre. Putting the peices together the Outer rim diameter of an alloy wheel has to be equal to the inner diameter of a tyre to be compatible with it.
Though the car comes with a set Alloy Wheel and tyres of a particular size you can also increase this size. This concept is called upsizing. So if for a particular car on our site you are able to see multiple options in the filter for Rim Diameter (R). It would mean that all the rim sizes are compatible with the car.
PS - This is one of the parameters for finding the compatibility of a tyre and alloy wheel. Secondly we will detail about the upszing in our other page.