Kumho 712's speed ratings?

[Larry C Leung]

My guess in the Kumho's is a stiffening band by the bead and a slightly
softer compound for more grip. The stiffener will reduce high speed tire
flex, thus reducing heat build up and centripetal tire diameter growth at
Z speeds. The softer compound means less treadwear, and stiffening band
means a stiffer ride and better turn in. AND a heavier tire. (It's this
way for all quality V+ speed rated tires). 

LL - NY

On Mon, 30 Apr 2001 11:21:32 -0400 Burl Vibert <blur at sympatico.ca>
writes:
>Perhaps it has construction differences such as a wrap of (or spiral)
>overlay over the belt package.  Could also be wraparound gum strips 
>on
>the belts, an additional extrusion of wedge compound, dual ply wraps,
>etc.  Basically to the driver, they are stiffer.
>
>Burl Vibert
>1987 5kcstq
>Kingston, Ontario
>
>
>Todd Phenneger wrote:
>> 
>> Some tire companies do this.   But the V-rated Kumho's
>> supposedly are a little softer sidewalls than the Z-rated but I
>> cant confirm this.  Sometimes its a tread difference as well.
>> Usually companies do this associated with a Tire Aspect ratio
>> change though.   Wierd,
>>   I always get the higher but sometimes maybe it doesnt matter.
>> They are both sure to be great tires, happy cornering.
>> l8r
>>
>> > I called a local tire shop yesterday and had them order a set
>> > of kumho
>> > 712's for my 4kq (with 15's). Anyway they asked what speed
>> > rating I
>> > wanted, I said the lower would be fine since my car can't get
>> > to 130,
>> > let alone 180 or whatever the high rating was. Now I have
>> > started to
>> > wonder, what is the deal with the same model and size of a
>> > tire coming
>> > in two different speed ratings for very similar prices? Does
>> > anyone have
>> > any idea what this is about? Is there any reason I should call
>> > them back
>> > and get the high rated tire?