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Re: [Healeys] TYRE SIZE for RIM

To: sebring@illawarra.hotkey.net.au
Subject: Re: [Healeys] TYRE SIZE for RIM
From: Dave & M <rusd@sitestar.net>
Date: Tue, 03 Jul 2007 21:48:51 -0600
Hi Joe,

In theory you may be correct. In reality, with radial tires which many
folks use, the tread tends to sit pretty flat but the sidewalls are
very flexible & so don't lend much to tire tread stability. Also,
inflation pressure affects the tread flatness very little on radials.

Radials feel down right squirmy  & always look under inflated when
compared to the other designs. Once you get used to the handling
quirks, they DO work very well although they have a rather sudden
breakaway when they let go. Much more so than a non radial design.

Many race tires are not radial & your concerns certainly do apply to
them. Many of us just prefer radials for street use.

Regards,
Dave Russell

sebring@illawarra.hotkey.net.au wrote:
 > I am a little perplexed at yhe variety and range of poinions and
 > sizes that are being listed for Healey rims.
 >
 > The metric system is very easy to understand. ie. 185 in the
 > 185x70x15 size designation is the nominal cross section width of
 > the tyre as designated in the industry standards.
 >
 > Now 185mm is 7.2 inches, or between friends, 7 inch rim width. The
 > recommended rim width for 185 will most likley range from approx.
 > 6.5 to 7 and a bit.
 >
 > 185 on 4.5inch rim would be way outside the acceptable range, Far
 > too much bag in the side wall and the tread may not sit flat and
 > therefore wear uneven, brake less than designed and handling likely
 >  to be sloppy due to side wall flex. The tyre will not carry its
 > designed lateral load. Alternatively 4.5 inch would equate to a
 > tire size of 115 !!! The smallest I am aware of is 145 0r 155 as
 > used on Beetles of old -- now thats a handling benchmark
 >
 > Check any race car where handling and braking is optimised and the
 > width apart of the tyre bead should be very close to the tread
 > width which should match ( within reason ) the rim width.
 >
 > Looking good is only one small part of the safety and performance
 > equation. The best power, the best brakes, the best suspension are
 > only as good as that little contact patch so please optimise it.
 > Pressure is also part of the equation to control this contact
 > patch. The wear pattern is only an indicator of how much of the
 > tread face/contact patch is in touch with the road surface and this
 >  controls braking and roadholding.
 >
 > Joe
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