> It is very possible that two tires from different mfg. will have a
> different tread width on the same nominally sized tire. For a
> very simple reason. The tire size has nothing to do with tread
> width.
>
> The 175 (or 185 or 165 or whatever) refers to the tire's maximum
> cross section when mounted on the rim width for which it is
> designed. When that tire is installed on a wheel with a larger or
> smaller rim width, the cross section will vary, too. A good number
> to go by is for every 1/2" change in rim width (smaller or larger),
> the cross section will change by about .2" (5mm). Thus if you take
> a say, 185 tire that was sized based on a 5" rim width and mount
> it on a 51/2" rim, it will actually be closer to 190mm wide. (but the
> tread width doesn't change).
Understood ... sizing is based on a specific rim width ... the tread
width is the tread width ... width of the cross section varies with
rim width ... how about the diameter? IOW, a 195/65R15 Dunlop
D40 M2 was sized for a 6.5" rim, has a tread with of 6.5" and a
diameter of 25.1" ... will the diameter vary if I install it on say
a 5.5" rim?
Safety Fast! ... larry.g.unger@lmco.com
'61 MGA 1600 MkII
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