Tire weight limits, Im confused

Discussion in 'Class C Motorhomes' started by Sharkysocal, Feb 26, 2007.

  1. Sharkysocal

    Sharkysocal New Member

    My 79 Dodge Sportsman, 24' Model Beaver has a GVWR of 11500 lbs.

    I Just bought it, and had Americas Tire put on the same tires it has specified on the door sticker. 8.00X16.50
    Only I changed from Bias ply to Radial.
    The tires are rated at 2040 lbs per tire. Thats only 12,240 lbs of weight.
    This only gives me 500lbs to load the bugger with.

    The tire shops I spoke with said I should be fine loading more then 12240 lbs on the RV because my tires are Load Range D. 8 ply.
    I can see us loading an additional 1450 lbs not counting a future small trailer that will haul my dirtbike and firewood and a large cooler.
    Can anyone please give me some advice here.
    Should I ask Americas tire to switch out the tires and get the next size up, which would replace my 8.00R16.5LT/105/ N /2040 lbs with 8.75R16.5LT /111/ N / 2405 lbs

    Below is a link to the Cooper tires I am talking about. Thank you in advance.

    http://www.coopertire.com/html/products/tires_lighttruck.aspx?page=srm_2_radial_lt :question:
  2. hertig

    hertig Senior Member

    Re: Tire weight limits, Im confused

    The GVWR is the maximum weight the RV can be, and includes the 'base' weight (or 'empty' weight) of the vehicle plus everything you put in it and on it. So your current tires can carry more weight than the RV is supposed to weight. You also want to check the axel maximum weight ratings (GAWR) front and rear to ensure that you don't overload either axel or the tires on that axel.

    Class C's are not known for their CCC or cargo carrying capacity. 1450 pounds of stuff and say 100 pounds of pin weight for a small trailer may be beyond the GVWR and or rear GAWR capability of your unit. Your best bet is to take it, unloaded, to a scale and find out what the overall weight and weight on each axel when empty except for the driver and gas/propane. Subtract these from your GVWR and GAWRs respectively and you will know exactly how much stuff, passangers and trailer weight you can handle. Don't forget that fresh water and sewage have weight too, say 8 pounds per gallon for a rough estimate.

    And it is wise to visit the scale loaded and ready to travel before leaving on a trip to make sure you haven't snuck over any of the vehicle limits.

    If the tire is rated at 2040 pounds, fully inflated, then that is all the tire can handle, I don't care what the load range or number of plys is. And the tire must be inflated to the specified pressure to handle even that much. And if the RV has a GVWR of 11500 pounds, then that is all it can handle. Note that 'can' does not mean you physically cannot overload a tire or GVWR, it just means that if you do, you are significantly increasing your chances of an unpleasant and/or expensive experiance.

    From what you say, I don't think you will receive any benefit from changing tire size, and there is a cost besides the likely cost to change - if the tire diameter is different, your speedometer/odometer will no longer be accurate, and if the width is different, the critical spacing between the dual tires may not be adequate.
  3. Sharkysocal

    Sharkysocal New Member

    Re: Tire weight limits, Im confused

    Thank you very much for teh great info.

    This is my first RV, and I dont want to waste money on the wrong tires n equipment.

    I will have it weighed asap.

    Take Care! :)
  4. utmtman

    utmtman Senior Member

    Re: Tire weight limits, Im confused

    There is also the GCWR which is the combined rating for your vehicle and pulling a trailer, toad, or anything else for that matter. Sadly some rv's do not put that number on the vehicle and you have to go to your books on the vehicle to find it. That numer can be as much as several thousand pounds or more above your GVWR. Example my rv is GVWR or 22000 and the GCWR is 26000. You could always transver some weight to your trailer and or toad if need be to adjust the weight.
  5. hertig

    hertig Senior Member

    Re: Tire weight limits, Im confused

    It may also be specified as maximum towing capacity, and then it would be only the maximum weight you can tow. Mine says 10,000 pounds, with a 600 pound pin weight. Unfortunately, the rear axel is only 1000 pounds under the maximum, so if I add a trailer with 600 pound pin weight, I can't carry much in the way of clothes or food (stuff which tends to be near the rear). Fortunately, I don't fill the water tank (also over the rear axel) when I drive, which gives me some extra cargo capacity.
  6. Stormin

    Stormin Member

    Re: Tire weight limits, Im confused

    So you really carry that much stuff that you don't fill your water tank on the road?
    What weighs that much, tools?
  7. hertig

    hertig Senior Member

    Re: Tire weight limits, Im confused

    I have a CCC of 3000 pounds, but only 1000 available on the rear axel and 2000 on the front. But most of the storage is in the rear.

    When I went from IL to MA with my dad and his stuff, we were within 100 pounds of the weight limits, front and rear. What weighs so much?

    Well, cat food and litter for seven cats, and their cage, and food for us, mostly. 1000 pounds of people and cats, in the front, fortunately. Tools, vacuum cleaner (got a new 'stick' one now, cleans better and doesn't weigh as much), extention cords, sewage macerator pump, air compressor (the ones at truck stops seem always broken), spare fluids, drinking water (I don't trust anything from the tap), bedding and clothes, books (including a huge box of manuals for the RV).

    But I don't fill my water tank not because I can't (could probably have a full tank when just the two of us and the cats), but because I don't need 100 gallons of water and don't want to pay the extra cost to transport it. So I only fill it until the first sensor registers. With our electrical needs, we hook up every night, so 25 gallons or so of water is plenty for a day or two. With my fifth wheel, I made do with about 10 gallons.

    Of course, if I was going boondocking, I would fill up before I left 'civilization'.
  8. Sharkysocal

    Sharkysocal New Member

    RE: Tire weight limits, Im confused

    Got it weighed!

    Holy cow, it weighs 9280 lbs!

    Thats a lot heavier then I thought it would weigh.

    Roughly gives me 1500 lbs to play with for waste, water, and other cargo weight.

    I just ordered some Bilstein heavy duty shocks. I hope that remedies the boat sway.
  9. wickedmouse383

    wickedmouse383 New Member

    RE: Tire weight limits, Im confused

    When I had my class c last year I went from D load range tires to E and did not change tire size and I did notice a significant difference in the ride (in a positive way) when loaded and when towing my race car. That was due to the fact that most D load range tires max @ 65 lbs. and the E max is 80 lbs. I gained more stability in the rear as well and not as much body roll.

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