[Shotimes] Tire Width

[Zach Leahy]

As has been mentioned, it really matters what your goal is on tires. 
I have run everywehre in the range of a 215/60/16 to a 245/40/17.  The
rim width is important becasue the sidewalls are really designed to
sit vertically, and not rolled in some amount.  By rolling in the
sidewalls a bit you decrease the effectivenss of them proportional to
the amount they are rolled in.  When you hit a bump, a strainght
sidewall transmits the force straigt through it to the rim.   With a
flexed in sidewall thee is some amount of an angle, and the force has
to be transmitted down that angle into the rim.  The result is that
the sidewall can flex more.  In general a bowed sidewall is not near
as stiff as straight one.

With that said, on full tread depth tires, it is hard to differntiate
(I cant) between excess sidewall movement and squirming of the tread
blocks.  I have often though my new tires handled worse than the old,
but it was the tread blocks moving about that I was feeling.  After a
lot of miles, the squirm was gone as the tread blocks became much
shorter and squirmed less.  This is the reason you can buy shaved
tires from places like tirerack.  My 93 does it on it's current ones
becasue the tread is still new and tall.

So a 225/55/16 on t a 6" slicer will have a bit more bow in the
sidewall than the same 215/60/16 would have.  It's not going to be too
bad though.  I ran 225/50/16's on slicers before and liked them.  What
will make a big difference though is the brand/make/model of the tire
and it's sidewall stiffness.  I have seen crappy bowed, soggy
sidewalled 215/60/16's and stiff sharp angled ones on 225/50/16's.  If
you head for a performance oriented tire you will get a stiff
sidewall.  It seems the softest ones I have seen seem to be on
Firestone Firehawks.  I have a set on my 92 (PO had the mon there, I
would never choose them) and they bulge and sway and are generally
lousy due to soft sidewalls.  I remember Kurt Metros had a set and he
hated them for the same reasons.  (So I'd avoid them).  The y make for
a nice soft ride, but handling will suffer.  In stark contrast, my
track tires have a sidewall stiff enough that they will support a
person sitting on them, while not mounted to a rim.  they will
actually support the weight of the car with no air pressure, or very
little in them.  These things have really stiff sidewalls that don't
give an micro-inch (ok, maybe 1 or 2 microinches - 1 microinch =
1x10^-6 inches).

So, results:  A soft sidewalled tire of 225/55/16 on a 6" slicer will
likely handle a bit worse than the same in 215/60/16 on the same
wheel.  A stiffer sidewalled tire will have a lot less negative
effect.

My choice would be to go with a tire that's nice and stiff, and get it
in 225/55/16 or 225/50/16.  I like kuhmos, but talk to your tire rep
and loko at other's ratings.  Tirerack is really nice for that becasue
you can get an idea of how a tire will work on your car before you buy
it.

Next step is to convince the wife to let you get some 8" rims.

Z

On 7/14/05, Ron Porter <ronporter@prodigy.net> wrote:
> If you replace the 225 tire with a better-quality 215 tire, handling in the
> wet or dry will probably improve.
> 
> The tread difference between a 215 and a 225 tire is negligible. Tread
> design ad compound are more important.
> 
> 6" rim is much better suited to the 215 tire.
> 
> After all that, steering response won't be quite as sharp with the taller
> profile tire. But, depending on the tire you buy, there may be no
> difference.
> 
> On bad roads, the 60-series will ride better.
> 
> Ron Porter
> 
> -----Original Message-----
> From: shotimes-admin@autox.team.net [mailto:shotimes-admin@autox.team.net]
> On Behalf Of Beisler Jonathon
> Sent: Thursday, July 14, 2005 9:23 AM
> To: Shotimes
> Subject: [Shotimes] Tire Width
> 
> Hey all,
> For once I'm not asking about a problem.  This is probably a matter of
> opinion
> more than anything, but I'll ask anyway.  Do you all think that I will see
> any
> difference in going back to the stock with of 215/60 after having 225/55?
> Other than the look of course.  By difference, I mean handling, etc.
> assuming
> tread, temp and speed ratings remain the same.  My tires have worn
> prematurely
> and I'm going to get like 33% off my next set, plus a freebie because it
> bubbled even with the tread indicators showing (God I love Discount Tire)
> and
> I'm contemplating going back to OEM size because I've thought the 225s have
> a
> sagging look to them on the stock rim.  I'm also thinking about new, bigger
> rims but the AWA is not amused by that right now.  Any thoughts, experience?
> Thanks,
> JB
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