Post by
SmithSR »
https://forums.nicoclub.com/smithsr-u5241.html
Wed Mar 31, 2004 2:25 pm
Glad you asked. There's simple math involved with figuring a tire's Overall Diameter, but I'll skip that and give you the sizes.
You've got 215/60-16 which, by the numbers is 26.16" tall (inflated but not installed with the vehicle's weight on it, aka 'static' measurement)
the 215/55-16 comes to 25.31" OD, by the conversion numbers.
To keep gearing, speedo, odometer and abs performing as OEM, you need to keep the tire's OD as close as possible to original equipment.
Keep in mind that each tire manufcturer builds to a different size spec. They're close, but if you measure two tires that are the same size from two different manufacturers, you'll see that section width(from outer-most part of sidewall bulge, on a manufacturer specified width rim), tread width, and sometimes the OD will be different.... ..it's as if they're all using a different sized tape measure..
So with all that jargon and mumbo jumbo to consider, the general rule of thumb is to keep the OD as close to OEM as possible.
the 215/55-16 is shorter. Maybe :bowdown Q45tech can figure the actual percentage of change from OEM.