Actual rim diameters?

[JHZR2]

Hi,

Ive read that the nominal rim diameter is not what you would measure if you checked out a wheel. For example, a 14" rin would actually measure closer to 15" and so on.

Is this the case? If so, how does one readuly verify the rim diameter to be correct if buying wheels?

Is there a standard "real" diameter for each wheel size?

Ive never measured, so I dont really know. Hope some experienced folks can verify...

Thanks!

 

[RamFan]

Yes this is the case. When I bought aftermarket 20'' rims for my Ram I measured them because something looked a bit off and they were actually almost 22''. I called discount tire and asked them about this and they told me that the "lip to lip" measurement is not the rims actual measurement. I believe the rims measurement comes from the inside of the rim.

 

[Hokiefyd]

Yeah, it's not the outside of the lip. The measurement is actually at the tire's mounting interface, which is the level plateau just inside of the lip.

 

[XS650]

From.... http://www.mgexperience.net/article/tire-sizes.html

 

[bdcardinal]

The wheel size should be marked on the wheel, usually cast into the wheel itself. At least any wheel I have purchased is that way.

 

[bepperb]

For reference, my 16" alloys are about 17.5" in diameter. Threw me for a curve when I got them.

 

[CapriRacer]

And you want another quirky thing?

14" rims aren't 14.000" at the bead interface. They are 354.8mm = 13.968".

And that sort of thing is true for ALL passenger tire rims.

Know what else? Motorcycle rims are done differently. They are actually larger than the dimension given - which is why you should NEVER put a pasenger car tire on a motorcycle rim!