Shayne k wrote:
I have a 2007 new body style chevy silverado 1500
4 wheel drive
Crew cab
Short bed
Factory hitch
3.73 gears
Towing capacity of 7500 lbs
We are looking to possibly purchase
2014 fun finder 266kirb
26' tt equaling 29'10
Dry weight of 5240
First -- the maximum allowable trailer weight (MATW) is not equal to the "Towing Capacity" (TC) of 7500#.
The MATW is equal to TC - "extras"
where "extras" is the combined weight of occupants, optional equipment, after-market additions, cargo, WDH, and anything else carried in or on the TV, when loaded for camping, which was not included in the TV's curb weight.
Second -- you must consider the TV's GVWR so the combined weight of "extras" and maximum vertical load (MVL) imposed on TV by TT does not exceed the TV's maximum payload (MPL).
The above two loading constraints give two equations:
MATW = TC - "extras", and
MVL = MPL - "extras"
The maximum vertical load, MVL = p1*p2*MATW
where p1 = percentage of tongue weight (TW) carried by TV with WD applied, and p2 = TW% = TW divided by MATW.
This allows us to calculate values for MATW and "extras" which will
simultaneously utilize 100% of Towing Capacity and 100% of TV's GVWR:
MATW = (TC-MPL)/(1-p1*p2), and
"extras" = (MPL-p1*p2*TC)/(1-p1*p2)
For example, with TC=7500#, MPL=1500#, p1=80%, and p2=13%:
MATW = (7500-1500)/(1-0.8*0.13) = 6000/0.896 = about 6700#, and
"extras" = (1500-0.8*0.13*7500)/0.896 = about 800#.
For this example, if the weight of "extras" is below 800#, the MATW can be greater than 6700#, and the trailer weight is limited by the GCWR. {MATW = TC-"extras"}
If the weight of "extras" is greater than 800#, the MATW must be less than 6700#, and the trailer weight is limited by the TV's GVWR. {MATW = (MPL-"extras")/(p1*p2)}
Although the published "dry weight" for the 266kirb is 5240#, a perhaps more realistic dry weight of 5555# is indicated in slide 24 of 24 on
this web page.
If you have an estimate of how much cargo and liquids you will carry in the TT, then the dry weight plus that estimate will tell you what to expect for a loaded trailer weight.
If you want to tailor the above process to your own specific parameters, you will need to know or estimate the following:
TV's Towing Capacity (TC)
TV's Maximum Payload (MPL) -- This value can be found on the drivers door edge or pillar, following the statement which reads "the maximum weight of occupants and cargo should not exceed" (or something to that effect).
Weight of "extras" -- either estimated or measured. Measured value is equal to TV's loaded-for-camping GVW minus the curb weight. Curb weight is equal to GCWR-TC.
Percent of TW carried on TV (p1) -- I recommend using 80%. Others like to use 100%.
Tongue weight percentage (p2) -- I recommend using 13%.
Happy calculating,
Ron