Kumho 712's speed ratings?

Larry C Leung l.leung at juno.com
Mon Apr 30 00:11:13 EDT 2001


The V-rated tires have a treadwear rating of 300, the Z-rated 240. 

The V-rated tires have a slightly less stiff sidewall, therefore are
likely quieter, and of smoother ride (the reality is, for a, by the
TireRack ratings system, ultra high perf tire, these are very quiet and
smooth, at least the V's are) than the Z's, the trade off at less than
warp speeds is that they will likely have slightly less turn in response
and possibly and I do mean possibly, slightly less ultimate dry cornering
grip (wet shouldn't be too big an issue, stiff tires tend to build up
slip angles faster, so they won't grip any better for the average high
perf driver)

Now, note, the performance differences (except wear) are probably
incremental, at best. Probably only a noticable difference in track
conditions, with a VERY experienced track driver (i.e. one who's
consistancy lap in lap out is of the order of a couple of percent,
qualities sought in tire testers for major tire makers, hmmm, I'd make
that a career goal...... I AM quite consistant in Autocross =-). 

The wear difference, by the UTG code is notable, and it is 20% tires
driven under the same conditions (or at least under the same conditions
as the UTG test which is done on a roller similar to what the TireRack
uses to heat cycle the DOT race rubber that they sell). Since I put a
decent amount of milage on my 200Q, I voted for the V-rated tires, as I
also don't intend to regularly track the 200, I've a GTi for that. So
far, I'm not sorry with my purchase.

As, Zora A Duntov (father of the Corvette, thick northern European
accent) said, "The difference is in de grease!" =-)

LL - NY

On Sun, 29 Apr 2001 19:10:24 -0700 Luke Rickert <rickert at engr.orst.edu>
writes:
>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? 
>
>thanks
>
>Luke 
>
>
>
>
>-- 
>Luke Rickert
>www.engr.orst.edu/~rickert



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