Yes, different tire makes can matter a lot, even in the same size.
Going from a 55 to a 50-series will sharpen steering response if they are
mounted on a proper rim. But, a 225/50 versus a 225/55 on a too-narrow rim
will also have a more severe sidewall angle with the shorter sidewall, which
"could" affect steering response enough to matter.
I liked my ES100s, but putting 225/55s on a slicer was not at all optimal,
and it was apparent when I had to run 50 psi hot to keep them from curling
under at a track.
When buying wheels, $$$ are better spent on rim width than on wheel
diameter.
Ron Porter
-----Original Message-----
From: shotimes-admin@autox.team.net [mailto:shotimes-admin@autox.team.net]
On Behalf Of leighsm
Sent: Tuesday, July 25, 2006 11:08 PM
To: Shotimes
Subject: Re: [Shotimes] Thoughts on Kumho Ecsta 711s, now tire/wheel fit
As I understand it; Jason went from a 225/55 to a 225/50 and stering
response
got worse. ( 2 different brands, all 16s) I checked some MFGR spec pages
and these size tires
have the same width (9.2"); same recommended rim range (6.0-8.0); and same
measuring rim size (7.0'). Where they differ drastically is overall height
(25.7' vs 24.9") and sidewall height (4.85" vs 4.45') and revs per mile (806
vs 835).
..
Going from a 55 to a 50 series tire would typically increase steering
response, and yet Jason got exactly the opposite effect. Since the new tire
is
exactly the same width as the old, and a shorter sidewall would increase
response if anything, I don't think the tire/rim fit had anything to do with
his sloppy steering feel. The tire is sloopier just because it is a
different brand of tire and has softer sidewalls. There can be dramatic
differences between brand models, even in exactly the same size.
..
The primary effect is the speedo will read 2.7 mph too high vs stock, twice
as much as before.
..
Recommended tire rim widths are very important however, and a 6 inch slicer
is the absolute minimum recommended for this size tire. Both sheer cornering
power (G's) and steering response would increase if you went to a wider rim.
Tire experts will recommend you try to stay in the middle of the range for
typical use. (7 inch) The lower limit (6 inch) sharply compromises the tire
performance. The maximum rim width (8 inch) is usually reserved for
competition situations where absolute maximum performance is demanded. The
difference from lower to middle is much more than middle to upper. G-force
limits could increase by 10% or so, while steering response increases are
usually even more dramatic, like removing 2 inches of slop from your
steering wheel. There is a compromise in ride harshness, but it is usually
pretty slight. If you want to optimize the performance of the car or the
tire, the tire/rim fit is almost as important as the tire brand selected.
..
The bulk of car enthusiasts do not consider the above paragraph when buying
tires & wheels. Just so long as it fits. (SHO members by nature are both
better informed and more curious than most other car enthusiasts.)
....
Unfortunately for us, Ford seems to typically fit wheels with a width on the
minimum side of the range. GM does a much better job of tire/wheel fit in
general, with wider wheels almost across the board. Ford obviously
emphasizes ride quality much higher than GM, and also higher than pure
cornering response.
..
Lee
ex-BFG chemist
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