tire wear speculations

[Phil Rose]

The other day while installing my summer tires/wheels, I checked the
depth of remaining tread. I made several depth measurements and
estimate that I've got no more than 30-40% of the original tread
depth remaining (above the wear-bumps). The wear pattern is pretty
uniform, although the tires have seen only a mere 15k miles of use in
street/highway driving. But they have also been used at *three* 2-day
track events (all mid-summer at Watkins Glen). If I continue to used
them just for street driving, I'd expect there'd be at least 8-10k
more miles remaining, giving about 25K miles (in addition to those 6
track days.)

So I've been wondering: just what "highway-equivalent" mileage might
be attributed to that track use? I realize that there are an enormous
number of variables (the track itself, experience level, temperature,
inflation pressure,....). But do you track-savvy folks use some
ballpark factor to estimate of the extra tirewear (per mile) from
track use, compared to normal driving? 5X? 10X? 20X?

I suspect my question is similar to asking: "How long is a piece of
string?" The tires btw are 225x60-15 Firestone Firehawk SZ-50es,
which is a Z-rated tire with excellent dry and wet grip (and super
quiet, too). It carries a very high rating for wear, although no one
seems to put much stock in such numbers.

Phil
(hoping for just one more track event on these tires)
--

Phil Rose				Rochester, NY USA
'91 200q	(130 Kmiles, Lago blue)
'91 200q   (57 Kmiles, Tornado red)
	mailto:pjrose at frontiernet.net