I put in my oem 225/50/17(se option) size from my 5th gen into the tire calculator as the original one. Then i put the 215/55/16 tire(standard) and it said the 215 tire was 2.137% too fast. What gives? Shouldnt they be the same if nissan put both of those wheels on our cars?

 

The calculator is just an approximation since each model is slightly different. FYI, the real way to tell how far off the speedometer will be is to compare the revs per mile for different tires (check the spec sheets for this info). The OEM crapenzas (P225/50R17) turned 804 revs per mile. That's my yardstick. My 16 inch snows turn 805 rpms while my 235/45R17 summers turn 820 rpms. What brand and model was the OEM 16?

 

Here are the calculated values for the various tire/wheel combinations. They are calculated or diameter and not checked for fit:

Wdth Aspct ratio Whl dia Tire dia
mm percent-----inch mm
Standard
205 65 15 647.5 --- 25.49

225 60 15 651.0 1% 25.63
245 55 15 650.5 0% 25.61
265 50 15 646.0 0% 25.43
205 60 16 652.4 1% 25.69
215 55 16 642.9 -1% 25.31
245 50 16 651.4 1% 25.65
195 55 17 646.3 0% 25.44
215 50 17 646.8 0% 25.46
225 50 17 656.8 1% 25.86
245 45 17 652.3 1% 25.68

The Std size is actually on a 15 inch wheel. The two sizes you have is actually 1%+ and 1%-. So both should be ok.

 

2% is not nearly enough difference to be concerned with (unless, perhaps, you're diagnosing a difficult ABS-related problem). Tire wear from full tread depth down to the wear bars amounts to more than a 2% variation over the life of any normal street tire.

Even the nominal width and profile information itself is only approximate. Not all 225/50 tires are exactly 225.00 mm wide or have a section height precisely half that. Never mind that both of these parameters will vary slightly with rim width. Even the tabulated revs per mile figure can be "off" slightly if you mount that tire on a wheel that's wider or narrower than its official "measuring rim" width.

Norm