well after much hunting i am still at a loss haha
The normal 17 inch alloys that come on the juke
are 215/55/R17 but i want to bumo em up to 18s.
Now i can get the right results by going 205/55/R18
or 215/50/R18 but i have no idea what these numbers mean.
Found a half decent explanation:
Tire sizes are expressed in the format WWW/AAXDD. WWW is the tire’s section width, measured in millimeters. AA is the aspect ratio or profile of the tire, which expresses the tire’s height as a percentage of its width. X is a letter indicating the tire’s internal construction. DD is the diameter in inches of the wheel that the tire is intended to be mounted on. An example of a tire size written in this format is 225/50R16.
This particular tire has a section width of 225 millimeters (8.86 inches). Section width is measured from the widest point of the outer sidewall - the side with the tire sizes and brand name that faces out from the vehicle - to the widest point of the inner sidewall when the tire is mounted on a specified width wheel. Narrower tires have lower section width numbers.
The next number is the aspect ratio. Tire sizes separate the section width from the aspect ratio with a slash. This tire has an aspect ratio of 50, meaning that the profile, or sidewall height measured from wheel to tread, is 50% of the section width. This number is also called section height; the higher the number, the taller the sidewall.
Tire sizes include a letter following the section height that is not a measurement, but an identification of the tire’s internal construction. This “R” indicates radial construction, in which the tire’s body plies “radiate” outward from the wheel’s center. A “D” indicates plies that crisscross diagonally, used for light truck or spare tires. Tire sizes with a “B” are belted and nearly obsolete.
The final number in the tire size indicates the tire and wheel diameter to be used together - in this case, 16 inches. These inch rim sizes are used on most passenger vehicles, while some tires used on heavy-duty trucks or trailers use “half inch” sizes, e.g. 14.5. Some manufacturers carry tire sizes that express rim diameter in millimeters, or that include different dimensions for the inside and outside edges of the tire. These tire sizes are intended for use with specific vehicles and should not be combined with traditional tire sizes.
Tire sizes follow the rim diameter with a service description, a code indicating load capacity and speed rating. This service description is required on all tires manufactured since 1991, except for Z-speed rated tires, which have tire sizes with a “Z” following the aspect ratio.
Yes, the rim width will decide on what tyres can be fitted but the dimensions you gave does not include the rim width. Say it's a 7inch wide rim this may take a tyre width of say 215 to 225 (only used as an example, not accurate).
A 215/55 will have a depth that is smaller than a 225/55 (depth = the tyre wall). As 55% of 215 is less than 55% of 225.
If changing tyre/wheels to a different size then you need to make sure the circumference is the same as the existingor your speedo and odometer will be in error.
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