The discussion seems to have stopped on one of the most important items on
the coach...tires, where the rubber meets the road. I have some very strong
feelings about tires (after having 2 blow on the same day). The last one was
a very violent explosion and I don't want to go through it again if
possible. I am installing Alcoa rims with Bridgestone LT225 tires this
winter. I had previously made it a point to look at the various
configurations of rims and tires when ever I have been around other GMCs. In
my humble opinion there are many coach owners that are either listening to
the wrong people or not understanding the information that has been
published by GMC on this issue.
The march 1997 issue of the GMC motorhome news published by Cinnabar had an
interesting article on Alcoa rims with subsequent information on the
recommended tires and alternative wheel studs. I urge you all to get a
compy and read it.
It starts by stating that the Alcoa classic wheel is the only recommended
rim because of its load carrying capability of 2780# versus the 2440# for
the LTS.
With regards to the tires, all D rated tires were recalled and replaced with
E rated tires by GMC in 1981 due to numerous tire failures. Tests were done
on the coach and it was found that under normal conditions when the coach is
standing still and the ride heights are properly set (how many times have I
heard the stories about various members system not working and they drive in
hold), individual wheel loads are no more than 2100 They than manipulated
the air suspenion and demonstrated loads as high as 3000 pounds on the front
tires and 2400 pounds on the rears. Under power the front tires load changes
due to the fact that they are the driving wheels. The rears have very high
opposing lateral forces when negotiating a tight curve ( I noticed that when
turning in a tight turn in a parking lot, the rear wheels almost drag across
the concrete).
With regards to tire sizes and types the article is very emphatic about
using steel belted sidewall tires of size LT225/75R16 load range E since it
is the same diameter as the original 16.5" tire and carrys 2680# at 80psi
cold pressure.
THEY DO NOT RECCOMEND LT235/85R16 TIRES FOR A VERY SPECIFIC REASON. If the
suspension is down and the coach is moved the tires will do considerable
damage to the coach. When the coach is moving and the tire blows or deflates
expect a lot of damage! This is because the LT235 is over 2.5" larger in
diameter that the LT225 and actually further lowers the 3.07 final drives
ratio. With them installed it also of course lowers the 3.42 installed final
drive negating the benefits.
With respect to the change of wheel studs when installing Alcoa wheels.
They are very firm about changing the studs since Alcoa demands it. On this
issue I am not sure since my observations show that there is still a thread
showing after the wheels are installed.
Just some more food for thought.
>-- [ From: Eugene Fisher * EMC.Ver #2.5.3 ] --
> Expanded recipient data:
> To: Eugene Fisher \ PRODIGY: (JDDP32B)
>
>I am going to make a GMC SAFETY CHECKLIST on my web page for New-Bees
>and Old-Bees GMC owners.
>
>There are many maintenance / upgrades that should be made to the GMC
>before they even hit the road. These are items that will hurt you or
>let you down. I would like to see your list of what you think are
>important..
>
> If you read the literature, the are many bad stories of coaches burned
>up, crashed with no brakes, etc. I think we can avoid most of these
>with good maintenance. This might become a prioritized list of
>maintenance items. But some of these are upgrades that do not appear in
>the shop manual.
>-----------
>SAFETY CHECK LIST
>
>Transmission vent, drain hose(vent has burned up several coaches)
>Steel gas line to the engine
>Wire electric gas pump through the oil switch and Ignition
>Replace fire extinguisher
>Replace isolation pads near the suspension tubes
>Test propane system for leaks / bad regulator
>Replace rubber brake lines
>Add a vacuum backup for the brakes
>Replace front bearings
>Replace rubber gas lines(including generator)
>Rebuild steering and suspension
>Replace tires over 5 years old
>Use auto-reset circuit brakers on rear lights and air system
>
>Please edit this list and add your items in priority
>gene
>
>
the coach...tires, where the rubber meets the road. I have some very strong
feelings about tires (after having 2 blow on the same day). The last one was
a very violent explosion and I don't want to go through it again if
possible. I am installing Alcoa rims with Bridgestone LT225 tires this
winter. I had previously made it a point to look at the various
configurations of rims and tires when ever I have been around other GMCs. In
my humble opinion there are many coach owners that are either listening to
the wrong people or not understanding the information that has been
published by GMC on this issue.
The march 1997 issue of the GMC motorhome news published by Cinnabar had an
interesting article on Alcoa rims with subsequent information on the
recommended tires and alternative wheel studs. I urge you all to get a
compy and read it.
It starts by stating that the Alcoa classic wheel is the only recommended
rim because of its load carrying capability of 2780# versus the 2440# for
the LTS.
With regards to the tires, all D rated tires were recalled and replaced with
E rated tires by GMC in 1981 due to numerous tire failures. Tests were done
on the coach and it was found that under normal conditions when the coach is
standing still and the ride heights are properly set (how many times have I
heard the stories about various members system not working and they drive in
hold), individual wheel loads are no more than 2100 They than manipulated
the air suspenion and demonstrated loads as high as 3000 pounds on the front
tires and 2400 pounds on the rears. Under power the front tires load changes
due to the fact that they are the driving wheels. The rears have very high
opposing lateral forces when negotiating a tight curve ( I noticed that when
turning in a tight turn in a parking lot, the rear wheels almost drag across
the concrete).
With regards to tire sizes and types the article is very emphatic about
using steel belted sidewall tires of size LT225/75R16 load range E since it
is the same diameter as the original 16.5" tire and carrys 2680# at 80psi
cold pressure.
THEY DO NOT RECCOMEND LT235/85R16 TIRES FOR A VERY SPECIFIC REASON. If the
suspension is down and the coach is moved the tires will do considerable
damage to the coach. When the coach is moving and the tire blows or deflates
expect a lot of damage! This is because the LT235 is over 2.5" larger in
diameter that the LT225 and actually further lowers the 3.07 final drives
ratio. With them installed it also of course lowers the 3.42 installed final
drive negating the benefits.
With respect to the change of wheel studs when installing Alcoa wheels.
They are very firm about changing the studs since Alcoa demands it. On this
issue I am not sure since my observations show that there is still a thread
showing after the wheels are installed.
Just some more food for thought.
>-- [ From: Eugene Fisher * EMC.Ver #2.5.3 ] --
> Expanded recipient data:
> To: Eugene Fisher \ PRODIGY: (JDDP32B)
>
>I am going to make a GMC SAFETY CHECKLIST on my web page for New-Bees
>and Old-Bees GMC owners.
>
>There are many maintenance / upgrades that should be made to the GMC
>before they even hit the road. These are items that will hurt you or
>let you down. I would like to see your list of what you think are
>important..
>
> If you read the literature, the are many bad stories of coaches burned
>up, crashed with no brakes, etc. I think we can avoid most of these
>with good maintenance. This might become a prioritized list of
>maintenance items. But some of these are upgrades that do not appear in
>the shop manual.
>-----------
>SAFETY CHECK LIST
>
>Transmission vent, drain hose(vent has burned up several coaches)
>Steel gas line to the engine
>Wire electric gas pump through the oil switch and Ignition
>Replace fire extinguisher
>Replace isolation pads near the suspension tubes
>Test propane system for leaks / bad regulator
>Replace rubber brake lines
>Add a vacuum backup for the brakes
>Replace front bearings
>Replace rubber gas lines(including generator)
>Rebuild steering and suspension
>Replace tires over 5 years old
>Use auto-reset circuit brakers on rear lights and air system
>
>Please edit this list and add your items in priority
>gene
>
>
