"mm" wrote in message ...
Thanks for your report. I have one question about what you've written. I
understand your conclusions related to tire aspect ratio, but why do you
relate tire speed rating to sidewall stiffness? My understanding was that
the speed rating primarily involved tires capacity to deal with heat.
Could
there not also be T or H rated tires with relatively stiff sidewalls?
Thanks.
Here is more of my limited understanding:

There are separate ratings for Treadwear, Traction and Temperature.

A different rating system applies to the speed rating. This indicates the
maximum speed the tire was designed for. So it is not a direct measure of
sidewall stiffness. However to survive at higher speeds the sidewall often
has to be stronger, and many tires designed to be driven faster also are
designed for cornering too. As a general rule a H rated tire will have a
stiffer sidewall than S or T, and a V rating is stiffer than H.

The variation between different tire models is probably as important also.
The best description of the qualities I was looking for with my application
were "Cornering Stability" and "Steering Response". [The original tires on
my Forester would barely respond to my steering input when towing].
You can see ratings for each tire model at www.tirerack.com.

See also:
http://www.tirerack.com/tires/tirete...eral/speed.htm
http://www.tirerack.com/tires/tirete...l/sidewall.htm

Also if you had the budget for it, going with a lower profile tire on a
bigger rim and maintaining the original outside diameter would sounds like
promising solution too.
http://www.tirerack.com/tires/tirete...al/plusone.htm


regards,
Chris