Tire Question...12R22.5

[Neil & Pat]

Hi Bill, thanks for the reply. I generally do not recommend that we
reengineer our vehicles, I would rather keep it as designed until it was no
longer possible to do so. Note, that I also use the 12R and have had no
problem getting them if I plan ahead just a tad. However, to respond to
your question please consider the following:

The 315/80R22.5 LRH is very close match for the specs of a 12R LRH, in
addition, its available in a LRJ as well giving it a major increase in
capacity. The comparable specs are as follows:

Spec 12R 315/80R
Wheel 9:00 9:00
section width 11.80 12.28
Max dia grown 43.61 43.15
Overall width 12.74 12.91
Tire spacing 13.5 13.82
LRH max load 7390/6780(120psi) 7610/6940(110psi)
LRJ max load na 8270/7610(120psi)

These are the critical numbers; you need to ascertain if the larger tire
will fit the wheel, coach and carry the load. It looks good for everything
except for wheel spacing and this is a critical area that I do not like to
see pushed (it true that some people consider this less critical for MHs
because the are used on highways only). With the correct wheels and
adequate room on the coach the 315/80 looks like an excellent choice, which
will operate at reduced air pressure to enhance the ride; our old coaches do
not have computers so the diameter differences appear to be negligible. I
don’t know how tight the FC coaches are (turning clearance is generally most
critical), you will have to check that out. I also do not know how common
the 315/80 tires are in the marketplace but at least you could use either
the LRH or LRJ at the appropriate pressure.

Regards,

Neil LeKander
Author “The RVer’s Ultimate Survival Guide”
author@...




Hi Neil,

Is there a higher weight rated, larger tire that is more available.
that you would recommend???

The 12R's are not available at many tire stores, usually ordered in
the area that I live, And finding a 12R on the side of the road
with a flat could be a problem. It would really be hard to find a
single matching tire replacement.

Bill 88 FC Michigan

--- In WanderlodgeForum@yahoogroups.com
, "Neil & Pat"
wrote:
>
> Hi John, you have already received several answers to your
inquiry; however,
> I thought that I would add a few additional thoughts. I believe
that what
> you are thinking of doing would not only be ill advised but may be
downright
> dangerous. From my years as a tire engineer and with A' Weigh We
Go
> weighing coaches including many Bluebirds (my own PT-36 included)
I have
> knowledge that most all late 90s Birds are very close to their
maximum GVWR
> or GAWR as delivered and many are over that critical (and legally
> enforceable) limit when operated.
>
> For that reason based on the lessor ability to carry a load the
11R tires
> are in no way suitable for use on your 98 LX. The actual load
capability
> for the 12R and 11R are #6610/7390 & #6780/6005 (single/dual)
respectively,
> thus, you can see that there is a major reduction in the tires
carrying
> capacity, probably less that your coach requires. On the slim
chance that
> your specific coach might be unusually light where the 11R could
carry the
> weight it will require an increase in tire pressure to do so,
something that
> most RVers hate to do because of the ride quality reduction that
accompanies
> higher tire pressures. In addition there is a approximately
a .75" radius
> reduction (affecting your computers and dash readouts) along with
a .80"
> reduction in tread width with a corresponding reduction in tire
footprint
> area (which will increase wear, decrease steering power and
decrease
> stopping power); finally while your current rims will probably be
OK to use
> they are not optimal for the 11R (9:00 vs. 8:25) a fact which will
also
> compromise somewhat the total tire performance
>
> Do not listen to those who are not unbiased experts in just what
tires are
> required for RV usage. Remember also that RV are the only vehicle
on the
> road that "operates at 100% of its capability 100% of the tire."
Tires are
> no place to compromise; there are some very important people on
board your
> coach. Do the right thing and have your coach weighed properly,
> wheel-by-wheel as is done by the RVSEF, only then will you be able
to make
> sound judgments re: tires, pressures, etc. If you have any other
questions
> or if I have misread your original question please do not hesitate
to ask
> additional questions.
>
> Regards,
>
> Neil LeKander
> Author "The RVer's Ultimate Survival Guide"
> author@...
>
> -----Original Message-----
> From: WanderlodgeForum@yahoogroups.com

> [mailto: WanderlodgeForum@yahoogroups.com
]On Behalf Of John
> Sent: Wednesday, October 11, 2006 6:44 PM
> To: WanderlodgeForum@yahoogroups.com

> Subject: [WanderlodgeForum] Tire Question...12R22.5
>
> I have started looking for new tires for our coach as it has the
> origional tires on it. While they are showing no cracking at all,
I am
> still concerned about their age and would like to start swapping
them
> out before I have to do it from the side of the road. The current
> tires are 12R22.5 which seems to be a lot more uncommon than
> 11R22.5s(which I run on my dump truck). From talking to a couple
tire
> people they say the 11R22.5 are a little smaller(shorter). Has
anyone
> switched from the 12s to the 11s? Any recomendations on a
particular
> brand?
>
> Thanks,
> John Cassel
> 98 Wanderlodge LX
>
>
>
> [Non-text portions of this message have been removed]
>



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