Forum Discussion
blt2ski
Jul 30, 2013Moderator
2oldman wrote:blt2ski wrote:Whaa.. is your driveway 30%? I don't think you'll find such a monster grade on any road you'd have any business on in this country.
For me, tow rating would include moving the total load up a 30% grade, The new tow specs from the SAE only have a min 12% grade you need to be able to go up. That is less grade than my driveway.
I'm on a clients 24% grade a few times a month on Queen Anne Hill/avenue in seattle. I have another client with a 33% grade on Lk Washington for 100 yds or so. Built a set of 6" rise x 18" tread steps up the side!
Was on another 20-22% grade per the sign in south King county a few weeks back. I see 15-18% grade signs thru out the area on a daily basis driving around. For those of us that have to drive these local hills, 12% is a nothing grade! as noted by another, rather soft, so the OEM's can have LARGE tow ratings. If one has to use there rigs in construction as I do, off road, 12% is nothing more than a shallow to low med grade hill to go up! I've had to run my bobcat up some 50-60% grades to get material up it. Even 45 degree's which is 100% upon occasion. One now that I think about, was over 1-1, probably 1.5-1 or 150% grade. Not that one will get a truck up that per say......
Hence why for me, 30% would be minumum! Need a few % points available for fudge. Along with depending upon the road type, one may not get to 30% if you are going up say green ashpalt, as it has more stick to it than cured concrete. Along with a given rig will need a few more HP to motovate yourself on a green asphalt grade than cured concrete. Gravel also needs more HP to move a given load down it! Bias ply tires use more HP than std radials, and 60-70 series radials use less HP than 75-85 series radials! Then depending upon the wind resistance of a given load, one may need upwards of 30% more or less than your base load!
Hence why in reality, one SHOULD have a hard time figuring out how much HP/Torque or low gearing one needs to properly tow a given trailer. I used to get better mpg pulling 18K down the road than I did 15K lbs of total truck and trailer. The 18K rig had low wind resistance, my TT on the other hand, used about 30 more HP at 60 mph than my 18K rig towing a bobcat! Hence why I got better mpg with the bobcat than my TT!
More to this game than ratings frankly!
marty
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