Re: [MV] HMMWV tires and rims.

From: Darrell Ramsell (daram@comcast.net)
Date: Wed Dec 22 2004 - 00:12:22 PST


Thanks everyone for your input.

I know as a rule of thumb that the bias tires should go on the 8 bolt and
the radials on the 12 bolt but I could never get the answer as to why. Now
I know. The only question I have now is what is each rim is rated for? On
the 8 bolt I've been told 25 to 35 psi and on the 12 bolt 45 to 50 psi.
Does anyone have a manual that shows what the actual max pressure for each
rims are?

I also received some good info from Cliff & George and I thought I would
share them with you.

On to tires/wheels.......You can use the radial tire on a Bias ply rim (and
that's what we refer to them as) but it is discouraged. its not what we
say, its what is written by the TMs. I did the swap of radials a few years
ago, in 29 palms, ca. and the rocks out there ate up the radials, 3 flats
in 2 days. BUT of course there was lots of driver error there too. I was
hauling ass, 50-60mph in most places. Along with all the rubble that is out
there, with a loaded truck. So that is why I got the flats. I would not
have done that if the extra tires were not around. I was driving about 2
hrs out to do stuff, so time was my friend/enemy, I had to be at camp by
dark......

As for the sway, I don't think anyone will be cognizant of the sway from
tire to tire. I would put the radials on anything. Much better tire. if I
could find some for my Deuce I would do that too!

The 8 bolt are designed for a working pressure of the tire, which if my
brain is functioning is around 35-40 psi... for the Bias tires, which
are run at no more than 30 psi per lube orders.. I run mine at 35.
The 12 bolt rims are for the higher working pressure of the
radials....which is 45-50 psi. The svc runs the radials at 35 psi.. I
run mine at 45. In both cases the military does not care about the
tread life, they are interested in being able to hit the beach, mud,
snow, or whatever w/o having to air up and or down for the terrain....

 From a engineering standpoint, the rims are engineered differently. The
8 bolt version does not have to compress the o-ring in the middle as
tightly due to the lower pressure, whereas the 12 bolt does for the
higher working pressure..... the more or less bolts are needed for even
compression of the o-ring so it will seat w/o leaking or blowing out.....

----- Original Message -----
From: "Glenn Shaw" <mpmutt@mtaofnj.us>
To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
Sent: Tuesday, December 21, 2004 8:22 PM
Subject: Re: [MV] HMMWV tires and rims.

Hi
I agree. They work OK. I have used them myself with radials on a light
trailer. The problem is the rims are only rated for 25 psi. You can go
higher but then your on your own I guess. The rim bolts do pop at times. I
have had 2 bolts pop but the rims held up OK. The 12 bolt is designed for
higher load and pressure. So if you want to use the 8 bolts, that OK but
you just have to be aware of the problem with pushing the envelope. So far
I have neve had a failure with the old 8 bolt rims but I wanted Darrell to
hear what the manufacturers recommendations are.

Regards
Glenn

-----Original Message-----
From: Julian Burke [mailto:julian@knology.net]
Sent: Tuesday, December 21, 2004 10:43 PM
To: Glenn Shaw; milveh
Subject: Re: [MV] HMMWV tires and rims.

Radial tires work just fine on the 8 lug rims with 10's of thousands of
miles logged and never a problem with several motor pools. You may not want

to do any serious 4 wheeling with the heavy variants but never had any
problems. Tire pressure should be 35 PSI on both radial and bias; any less
and you will have "square" tires and premature tire wear and failure.
Julian

Hi
No radials on 8 bolt rims. Not rated for radial use or pressure. Best is
radial tire on 12 bolt rim at proper pressure.

Glenn

-----Original Message-----
From: Darrell Ramsell [mailto:daram@comcast.net]
Sent: Tuesday, December 21, 2004 4:17 AM
To: Military Vehicles Mailing List
Subject: [MV] HMMWV tires and rims.

Gents

I've been researching information as to which HMMWV tire (Radial or Bios) is

better to use on my M-101 trailer. I've collected my information from
talking to military vehicle mechanic from just about every base within a 100

of San Francisco, Army, Marines Reserve and National Guard units. I've
also talked to some tire shops and the tire manufactures. Here is what I've

learned.

The Bios are better for use on the trailer because they provide a better
ride. This is because the Bios have thicker sidewalls which makes it less
prone to swaying. Since radials sway more than the Bios tires, some say
that this makes the radial more prone to poping the bead when driving in
rough terrain and hills. That said, some of the Marines that I know who
work in the motor pools at various bases around the Bay Area said that
they'll put radials on the trailers if they have the chance. The radials
will cause the trailer to sway a little but apparently not enough to be a
big concern. The main reason they prefer the radial is that they can use it

as a spare tire for the HMMWV. They've been told that it's not a good idea
to mix the radial and bios tires on the same vehicle. The other reason is
that they feel the tires are stronger because they are radial and that they
have a higher weight rating than the Bios.

Another thing that I was researching was the 8 bolt vs the 12 bolt rim and
which tires go better on which rims. I found out that both tires are
compatable with both rims. What make a difference is the weight of the
vehicle that they'll be supporting. I've been told that the 8 bolt rims are

designed for axle weights of under two tons. The 12 bolt is for above two
tons. So, if I understand this correctly, any HMMWV that has a weight of 4
tons or less will be fine with any tire and rim combination but anything
heavier should use the 12 bolt with radials because they can handle the
higher weight loads.

Well I hope you find this useful and if anyone has anything more to add I be

glad to hear it.

Darrell

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