Home » Public Forums » GMCnet » [GMCnet] Overloading Tires
| Re: [GMCnet] Overloading Tires [message #326066 is a reply to message #326065] |
Thu, 16 November 2017 09:39   |
James Hupy
Messages: 6806
Registered: May 2010
Karma:
|
Senior Member |
|
|
I never recommend INTENTIONALLY driving your quad bag equipped coach on 3
tires, EXCEPT to move it and your family out of harms way. We recently had
one of our members coaches totaled, and one family member injured enough to
require an ambulance ride to an emergency hospital, by an oncoming vehicle
colliding with their coach when it was pulled over on the shoulder of the
freeway with the emergency flashers on. Drive it that way only far enough
to remove it from harms way, NO FURTHER.
JIM HUPY
SALEM, OR
78 GMC ROYALE 403
On Nov 16, 2017 7:24 AM, "Rob Mueller" wrote:
> G'day,
>
> Below you will find the email I send in every time this subject comes up.
>
> OPERATING A GMC ON LESS THAN FOUR REAR WHEELS/TIRES
>
> REFERENCE: GMC Motorhome Operating Manual X-7821A Page 1 - IMPORTANT
> INFORMATION ON VEHICLE LOADING.
>
> http://www.bdub.net/manuals/X7821A.zip
>
> GVWR (Gross Vehicle Weight Rating) represents the maximum permissible
> loaded weight of the vehicle.
>
> 26 foot GMC GVWR = 12,500 lbs
>
> GAWR (Gross Axle Weight Rating) the maximum weight that the axle can carry.
>
> 26 foot GMC GAWR
>
> GAWR = 4,500 lbs Front Wheels
> GAWR = 8,000 lbs Rear Wheels
>
> REFERENCE: Tire Load Range: http://gmcmotorhome.info/tires.html
>
> Tire Load Range: The max load a tire can carry and the pressure required
> to carry that load.
>
> D load range max load @ 65 PSI = 2,235 pounds
>
> E load range tire max load @ 80 psi = 2,680 pounds
>
> REFERENCE: Alcoa Light Truck, SUV, RV and Motorhome Wheels Fitment Guide
>
> http://www.southwestwheel.com/pictures5/LTFitment-Screen_10-18-01.pdf
>
> P/N: 160231
> Style: Classic
> Max Wheel Load Pounds: 2780
> Capacity ratings as dual or single in highway service - bias-ply or radial
>
> P/N: 160251
> Style: LTS 5
> Max Wheel Load Pounds: 2440
> Capacity ratings as dual or single in highway service - bias-ply or radial
>
> P/N: 161251
> Style: Hot Shot
> Max Wheel Load Pounds: 2780
> Capacity ratings as dual or single in highway service - bias-ply or radial
>
> COMMENTS:
>
> The weight distribution per tire would be dependant on the how much
> pressure was supplied to the air bag supporting the remaining
> tire. For ease of calculations we'll divide the rear GAWR of 8,000 lbs as
> noted above by four which results in a load per tire of
> 2,000 lbs. Operating the GMC with one wheel removed the load on the
> remaining tire would double; going from 2,000 to 4,000 lbs. This
> is an overload of 1,765 pounds (~79%) on a D range tire at the maximum
> pressure of 65 psi and an overload of 1320 pounds (~49%) on
> an E load range tire at the maximum pressure of 80 psi. If the tires are
> not inflated to the pressures noted in the previous
> sentence the overload would be even higher.
>
> CONCLUSION:
>
> If you drive your GMC with less than four rear tires supporting the load
> you WILL be operating the GMC with OVERLOADED TIRE(S) and
> OVERLOADED WHEELS!
>
> Regards,
> Rob M.
> The Pedantic Mechanic
> Sydney, Australia
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
> USA '77 Kingsley - TZE 267V100808
>
>
> -----Original Message-----
> From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of
> Richard Denney
> Sent: Thursday, November 16, 2017 8:56 AM
> To: gmclist@list.gmcnet.org
> Subject: Re: [GMCnet] Overloading Tires
>
> Of course, the loading is determined by the load rating based on inflation.
> The nominal load rating is based on full inflation (80 psi for Load Range
> E, as we usually use).
>
> Looking at Goodyear's chart, the maximum load for a light truck tire at 80
> psi is 2680 pounds (65 mph top speed). Last I weighed my coach, it was 5725
> pounds on the rear. Half of that is 2862, which overloads a fully inflated
> E-range tire by 7%. So, if I was facing that eventuality, and had the
> capability to lift a dead tire, I would first put the dead tire on the
> middle axle (to move the pivot point back and increase the load on the
> front tire), and then inflate the good tire to 80 psi. Then, I would go
> slow for the minimum possible time (Goodyear recommends no faster than 55
> for a 9% overload). Since I don't have those capabilities, I won't worry
> about it. :)
>
> I usually run 50 psi in the rear. According to the chart, the maximum rear
> tire weight of 1500 pounds for my early, lightweight coach needs 40 psi,
> and I add 10 psi for higher speeds, per their chart. At that pressure, the
> 65mph-limited load is 1765. 2862 is a 65% overload, for which Goodyear
> recommends a 10 psi increase in pressure and a 14 mph speed limit. But
> because the tire is well below it's rated pressure, I can increase it to 80
> psi and have only a 7% overload.
>
> If my rear weight was 2000 pounds per tire (8000 pounds total on the rear),
> Goodyear wants me to run 55 psi in the rear, plus the 10 psi for high
> speeds. 4000 pounds on one tire (with the other lifted) would be a 50%
> overload of an E-range tire at 80 psi. Goodyear suggests I can carry that
> load if I inflate the tire above its maximum rated inflation by 10 psi and
> limit my speed to 14 mph.
>
> Here's the Goodyear chart, which includes advice for overloads:
> https://www.goodyeartrucktires.com/pdf/resources/publications/2010_
> loadinflation.pdf
>
> Rick "You brought your second purse? Well, dammit, I have to recalculate
> all my inflation pressures!" Denney
>
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
|
|
|
|
Current Time: Mon May 13 16:40:44 CDT 2024
Total time taken to generate the page: 0.72373 seconds
|
GMCforum
Search
Help
Register
Login
Home
