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Gross vehicle weight & tire pressure
Yahoo Message Number: 135571
OK, I read through Andy's excellent Eureka!Live primer on tire safety and went ahead and had our rig weighed this morning. (If you live in OC, O'Neil storage off the 55 @ Edinger has a pubic scale. They charged me $10 to weigh total, front/back and left/right.)
 Like standing on scales after the holidays, actually weighing your RV is a real eye-opener. For my 1993 22' MP, LD lists the dry weight @ 8,084. However, I'm assuming this is for the standard Chevy 350 - my rig has the optional 454 tbi and a bunch of heavy-duty upgrades (4L80E tranny, rear-end, double radiator for oil/tranny cooler, etc).
 With a full 22 gal tank of gas, 10 gal propane, 6 gal hot water, a rooftop AC, a kitchen full of 'stuff', and storage bins full of tools, camp stove/tables/chairs, etc, the total weight was 9,360 lbs. Throw in 500 lbs for passengers and another 140 for misc food/etc, and I come in at 10,000 lbs. The GVWR is 10,500, so I have a CCC of 500 lbs.

***
 From my primitive front/rear measurements, I got a distribution of 38.8% front & 61.2% rear. (Does this appear reasonable?) I just sort of eyeballed the midway point between the front/rear axles. As above, I think the 454/4L80E might be coming into play to push some weight forward.
 So, with 3,880 lbs in the front and 6,120 lbs in the rear, my individual tire load is 1,940 in the front (divide by 2) and 1,530 in the back (divide by 4).
 Again, following Andy's advice, I got hold of the tire pressure/load chart for my new tires, and cross-referenced it to the loads above. For my specific case, the chart is showing 50-55 psi for the front tires and 45 psi for the rear tires.
 Does this appear within the range of experience for others who have gone through this exercise? Anything glaring out that appears to be an anomaly? I'm going to hold off adjusting the tire pressure until I get some supporting input.

TIA,

Karl
Re: Gross vehicle weight & tire pressure
Reply #1 –
Yahoo Message Number: 135573
No, you have much more than 500# of CCC.
 CCC is the GVWR (in your case, 10,500#) minus weight weight (full fresh water, propane, fuel) minus the sleeping capacity weight rating (number of sleeping positions x 154#).  The resultant number is how much "stuff" you can load into the vehicle.  Since you've already included "stuff" in your weight figure, the 500# is just how much *remaining* CCC you have left, not your total CCC.

Linda Hylton http://earl-linda.blogspot.com
Linda Hylton
Re: Gross vehicle weight & tire pressure
Reply #2 –
Yahoo Message Number: 135575
Quote
Again, following Andy's advice, I got hold of the tire pressure/load chart for my new tires, and cross-referenced it to the loads above. For my specific case, the chart is showing 50-55 psi for the front tires and 45 psi for the rear tires.
 Does this appear within the range of experience for others who have gone through this exercise? Anything glaring out that appears to be an anomaly? I'm going to hold off adjusting the tire pressure until I get some supporting input.

TIA,

Karl
Karl, that seems awfully low to me. Others will chime in. Just for comparison, based on the one time I had my '02 30' weighed (at nearly full CCC), the charts called for 60lb front and 70lb rear. I've kept that pressure through 3 sets of tires and have had no unusual tire wear.

Chris
Formerly: 2002 30' IB
Re: Gross vehicle weight & tire pressure
Reply #3 –
Yahoo Message Number: 135576
Sorry, that's (sort of) what I meant. I should have been more accurate and labeled my result 'net CCC'. Since I already have the RV loaded, I was thinking in terms of what add'l items (if need be) I could safely add.
 I understand the gross (ie total) CCC is an important number for people shopping for an RV. In their case, they're not interested in any add'l stuff, they want to know the total amount of things they can bring along out of the gate.

***
 As for my tire pressure calculations, I realized I could assume a 35/65 front/rear distribution to somewhat mitigate my ad hoc measurement. In this case, I can set the rear tire pressure to the higher 65% number, but retain the front @ the original 39% result.
 Looking at my chart, 55psi can handle up to 1,875 for the duallies, and 2,060 for the singles. This provides me a safety cushion for both front & rear by around 5psi.
Re: Gross vehicle weight & tire pressure
Reply #4 –
Yahoo Message Number: 135577
Chris, I just added an update to my original post. I thought the numbers might be a little low, so I decided to fudge the rear weight distribution numbers.

If I shift the weight to 35/65, then my weight per rear tire comes
Re: Gross vehicle weight & tire pressure
Reply #5 –
Yahoo Message Number: 135578
Quote
"...the charts called for 60lb front and 70lb rear. I've kept that pressure through 3 sets of tires and have had no unusual tire wear."

Chris
Chris
 Your experience mirrors mine in an '04 30'IB. I routinely carry 65# in front and 75# in the rear. It's comfortable and I see no wear.

Steve S.
Lazy Bones & Jiggs
Steve S.
Lazy Bones & Cedar
2004 30'IB (Island Bed)
Yesterday is History, Tomorrow is a Mystery
Live for the day!
Re: Gross vehicle weight & tire pressure
Reply #6 –
Yahoo Message Number: 135579
One suggestion.  I would take the measured front and rear weights, add the passenger weight to the front weight and the net "CCC" weight to the rear axle weight.  That should give a pretty good estimate of your fully loaded axle weights.  Then use the tire chart and add 5 psi to each if you wish.  FWIW: Jack
Re: Gross vehicle weight & tire pressure
Reply #7 –
Yahoo Message Number: 135582
"that seems awfully low to me... Just for comparison, based on the one time I had my '02 30' weighed..."
 Yes, but let's keep in mind that Karl's rig is a 1993 22' Multiplan. That means it's built on the old Chevrolet G30 chassis, with a GVWR of 10,500 lb.--about 4,000 pounds less than your thirty-footer, Chris. Lower tire pressures are to be expected with these older, lighter rigs. I say Karl should follow the recommended pressures for his tires and his load.

Andy Baird http://www.andybaird.com/travels/
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
 
Re: Gross vehicle weight & tire pressure
Reply #8 –
Yahoo Message Number: 135586
Andy & others, once again, thank you for the responses & tips. I feel fairly confident that 55psi all around will be well with