Gee, and I thought that BFG was the DARK SIDE!!!!!!!!!!
dg50@daimlerchrysler.com wrote:
> On a completely non-turbo related subject...
>
> I had a hell of a time in Harrisburg this past weekend, taken quite literally.
> The car was slipping and sliding around all over the place (decidedly NOT the
> behaviour you want in a high-speed slalom), driver confidence plummeted, and I
> never did put together a run that was anything near competitive.
>
> Once the red mist had cleared, I went looking for what could be the cause, as
>I
> had had similar problems in Virginia, and quite possibly Peru too.
>
> On impulse, I had stuck a pyrometer into the tires once I had cruised back to
> the pits, and found that, even after 4 runs (and taking into account the
>cooling
> effect of my trip back) the tires were still pretty cold - 120 front, 100
>rear -
> on tires that want to be somewhere up around 160-200.
>
> I also overheard a few fellow wide-tire g-force drivers bitching about how
>their
> tires never got up to temperature and so slid around, and it suddenly fell
>into
> place. When hot, the g-forces are phenomenal, but cold, they frankly suck. The
> evidence is there - a car nearly identical to mine, running much narrower "old
> R1s" didn't seem to have nearly the grip problems that I did.
>
> My g-forces have been wearing really well, I have nearly 60 runs on them, and
>I
> expect to see about 20 more, but it's getting near time to buy tires. I have a
> choice to make:
>
> 1) Stick with the g-force, but drop down a size, to 255-40R17
> 2) Switch to Kumho, at 275-40R17
> 3) Both, a Kumho 255-40R17
>
> That's right, the Dark Side of the Force, the K-tire, is beckoning me from the
> shadows.
>
> Here's the relevant data:
> Section Tread Diameter
> g-force 275-40R17 10.6 10.1 25.6
> g-force 255-40R17 9.9 9.7 24.7
> Kumho 275-40R17 11.18 10.39 25.35
> Kumho 255-40R17 10.63 9.72 24.80
>
> Interestingly enough, the big K-tire is both wider and shorter than the big
>BFG.
> The Kumhos are also much more "bulbous" than the BFGs - you get less tread for
> the section width.
>
> But here's the $10,000 question - how good are the K-tires, both hot and
>cold? I
> understand that a hot g-force is a better tire than a hot Kumho, but is a cold
> Kumho better than a cold g-force? Or is it better to stick with the BFGs, but
> move down a size (and so get a lower car and better gearing, but less grip
>when
> hot?)
>
> Any thoughts?
>
> DG
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