Forum Discussion

CAJW's avatar
CAJW
Explorer
Aug 22, 2013

GAWR, how close are your to it?

Sorry about yet another thread about weights, but searching the forum, I couldn't locate a specific discussion regarding GAWR regarding operating near the limit. Mello Mike has a good write up about weights in general and I found a thread about brake design and fluctuations in weight loading depending on driving conditions.

My specific question is: How close are TC owners operating to their GAWR and any ill effects?

I'm concerned about putting a 400lb.(including carrier) dual sport on the back of my rig which will put me over GVWR by about 500 lbs. I've read enough about this exceedance that I'm ok with that. My main concern is it'll put me at 150 lbs. under the GAWR. Will dynamic loads exceed the GAWR or is that figured into the equation by manufactures when they set the limit? I tried mocking up the bike on the front bumper, but it won't work for me and also puts me very close to front GAWR. Comments?
  • CAJW wrote:

    Will dynamic loads exceed the GAWR:
    ans: Yes

    Is that figured into the equation by manufactures when they set the limit?
    ans: Yes

    Comments?
    ans: Load it up; you're good to go if you are under (static) the GAWR. Just remember, 500lbs on an extended hitch will put much more than 500lbs on your rear axle. On a long wheelbase/8' bed truck, 500 lbs on a 24" extended hitch will put about 1,000lbs of force on the rear axle.


    Brad
  • So are you saying you are 500 pounds over your tire ratings. That is usually the limiting factor. My 2011 Chevy 1 ton SRW GAWR (rear axle 7050) is exactly what the tires are rated for. The axle itself is rated somewhere around 11k. When I put my TC on with no water and just me I have about 380 payload left. When I get everything in I will be over a couple hundred pounds with my boat behind me which has a 250 or so tongue weight on a extended hitch. It still handles very well. I will get heavier duty tires when my present tires wear out. I also only travel at 60 mph or less with truck camper and boat in tow.
  • dave17352 wrote:
    So are you saying you are 500 pounds over your tire ratings. That is usually the limiting factor. My 2011 Chevy 1 ton SRW GAWR (rear axle 7050) is exactly what the tires are rated for. The axle itself is rated somewhere around 11k. When I put my TC on with no water and just me I have about 380 payload left. When I get everything in I will be over a couple hundred pounds and I will still put my boat behind me which has a 250 or so tongue weight on a extended hitch. It still handles very well. I will get heavier duty tires when my present tires wear out. I also only travel at 60mph or less with truck camper and boat in tow.


    Here are the specific numbers I'm working with:
    GVWR 13,025
    GAWR front 5600
    GAWR Rear 9375
    Tires "E" rated 3085 single, 2835 Dual

    Truck with Camper loaded (incl 20 gal. water/stuff, full fuel & pax, without Motorcycle or carrier) 13,150

    Above with full water 13,800 (Scale actual front 5040, rear 8760)
    Motorcycle and carrier 400 lbs.

    With the above tire ratings, I figure the following:
    Max front 6170, max rear 11,340.

    Looks to me that I'll be at 9160 rear axle with full water and motorcycle + carrier or 2180 under max tire loads for the real duals. GVWR will be (w/ full water) 14200 or 1175 over GVWR, but under on each axle. (Front by 560, rear by 215). Water can be backed down to 20 gals. or less to improve on these numbers.
  • When you add 400lbs behind your bumper; you will add about 800lbs to you rear axle and take about 400lbs off your front axle.

    Your rear axle will see about 9,560lbs, not 9,160 lbs. The exact added force on your rear axle depends on your wheelbase and the distance the m/c c/g is behind the rear axle.
  • There are people here that may not be comfortable with this but I would be. Especially sense you are well within your tire ratings. I basically run a little over on my ratings but not a whole bunch. With my boat in tow I run a few hundred pounds over my GVWR. But like I said I don't run 75 mph down the interstate, when fully loaded. I would think that rig would handle your load very well. The new Duramax's sense 2011 are a whole different world. I think your rear axle itself is rated at like 11k not sure though. I realize GVWR is about the brakes,transmission and the whole ball of wax not just your axle's or tires. I wouldn't run super high speed fully loaded, but that is JMHO. Obviously the best bet is to be under on all numbers.
  • If you start getting close to OEM rating limits, you need to find which component has the lowest rating and upgrade it. The rear of my truck (which uses the same frame, engine and transmission as the DRW 1t) had 6100 lb rated tires on 7000 lbs rims, 7000 lb suspension and a 9750 lb axle. I replaced the rims and tires to get 9610 lbs of tire rating, but am actually limited to 9000 lbs due to my rim choice. The suspension was upgraded to handle 9000 lbs and now I feel confident I am not above the ratings of the currently installed components.