Re: ihc-digest V5 #136

[John Hofstetter <hofs@domain.elided>]

>Let's keep in mind we're talking about obsolete size designations and load
>ratings(and I threw that in...)that are still in mixed use for some things.
>Bias ply tires are disappearing from normal tire distribution, but are
>still available from 'collector' tire places so I doubt the old sizes will
>go away completely any time soon. With the old bias ply sizes, a general
>rule of thumb is the unloaded diameter at max pressure is roughly 2xstated
>width+rim diameter. For a 7.50x16, that's (2x7.5)+16, or 31". Makes for
>about a 29.5 or 30" tire effective at normal operating pressures and loads.
>This works for tires in sizes *.00 and *.50, if you see a *.60 size that's
>a 'low profile' bias ply size that equates to maybe a /75 series aspect
>ratio in a radial. OEM rims for 7.50's would have been 5.5 or 6.5" wide
>across the inside of the bead seat. The only available 16" bias ply
>sizes(truck tires) in this day and age are 6.00, 7.50, and 9.00. The
>9.00x16's on my S-120 are about 34" tall, 9" across the casing, with a 7.5"
>wide tread. I doubt you'll find anything in truck sizes that's not at least
>6PR. Last I looked, you could get highway tread, mud lugs, or military
>NDT's.
>
>In radials, a 235/85-16 is a tiny bit bigger than a 7.50x16, with an
>unloaded diameter of about 31.5" and a casing width of about 9.5". Most
>radials aren't going to show a 'ply rating', so looking at the max pressure
>is a good way to tell unless you're a pro reading weight capacities.
>
>For pre-'69 4x4 Travelalls with stock suspensions, I can confirm that a
>Gateway Buckshot Mudder in PR78-15(32x10.5) fits with no apparent clearance
>problems. They suck on the street, but they fit.
>
>Jim

Jim,
I'm impressed. I knew that I didn't know much about tires and now I really
know I didn't know much about tires and what I did know is mostly obsolete.
How do you happen to know so much about tires?  By the way, they probably
don't have them now, but about a year ago I bought two 7.50 X16 tires from
Costco. Now for a personal question. I know for sure the Michelins on my
Travelall were 7.50X16, so is my memory faulty on the part about them being
radials, or did they change the nomenclature later on, or what?  Was the
fact that the one-time-only cap that I got from the specialty dealer
seldom stayed on very long, because they were radials?  Straighten me out
Jim, please.
John



John Hofstetter, who nets at   http://www.goldrush.com/~hofs
PROBABLY MORE TO REMEMBER THAN EVER REALLY HAPPENED
Owner of 79 Scout Terra  with 8000 lb. Warn Winch,
Detroit Locker in rear and LS in front,
 4" Trailmaster lift    Holley E F I  Mallory Unilite Dist.   MSD ignition
Too darn long and too darn wide  to always go where I ask it to go.
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