historical accuracy, was: <VV> Tire gurus

[airvair]

All this discussion brings up a point. With regard to historical 
accuracy, is it better to preserve the factory LOOK of the (factory 
stock) car, or it's speedo's mechanical accuracy? In this case, is it 
better to have a tire with the diameter that LOOKS like an authentic 
7.00-13, or one who's size is chosen merely to allow the speedo to 
function accurately? And if radials end up adversely affecting the look, 
should they be banned in stock classes?

As stated before, I dislike the undersized look of (most all) present 
radial tires. Like any car, wide-open wheel wells (what you get when the 
tires don't fill the openings) don't look good. The downside is that 
with 13" wheels, it looks like we are pretty much stuck with 
undersize-looking tires (when they're radials.)

-Mark C

Bruce Schug wrote:

>
> On Mar 27, 2005, at 1:46 PM, John Dozsa wrote:
>
>> Mark,
>>
>> I just bought eight 185/80R-13 white wall tires that closely match the
>> original 7.00-13 tires.  Delta Brand.  Tires are marked "Made in
>> China".  Spec sheet link at
>> <http://www.deltatire.com/catalog/tirelist.asp?tCatID=3>  OD is listed
>> at 24.5 inches.  Don't know if it's static or rolling diameter.  The
>> circumference measures 78 inches, inflated tire mounted on stock late
>> model rims.  Calculated OD = 24.83.  In better spring weather I'll
>> measure rolling diameter.
>>
>
> John,
>
> These manufacturer's "diameter" figures are always static overall 
> diameter, (the tire mounted on a wheel and inflated but not loaded) 
> unless otherwise noted.
>
> The actual static overall diameter of an original 7.00-13 was about 
> 25.3", significantly larger than any 185/80-13 I've ever seen.
>
> This is why Mark wrote that the 7.00-13 is larger in diameter and 
> LOOKS larger on a car than a 185/80-13.
>
> However, because of the difference in bias ply tires, like the 
> 7.00-13, and modern radials, like the 185/80-13, the revs per mile or 
> rolling diameters of these two tires is not proportional to their 
> diameters. The 185/80-13 will still not have the same rolling diameter 
> as the 7.00-13, but, because of these different characteristics, there 
> won't be as much difference as there is in diameter.
>
> Understand?
>
> Bruce