Best Diesel SUV Tow Vehicles?
We're getting a 25 ft. Airstream travel trailer and would like to tow it with a diesel SUV. The trailer has a Gross Vehicle Weight of 7300 lbs. and the Mercedes-Benz GL350 we're considering has a maxi...
Forum Discussion
horton333 wrote:rjstractor wrote:4x4ord wrote:
It is too close to call. After posting that remark I read it and realized what I meant to write was:
A 240 HP GL350 pulling a 7300 lb Airstream up a hill should be able to keep up with a 440 hp Powerstroke pulling a 17000 lb fiver up the same hill.
I'd put the money on the GL350 with the Airstream any day. It has a slight hp and torque versus weight ratio but the kicker is the rig pulling the Airstream is using less power to overcome aerodynamic drag. Conversely the PSD pulling a 17K flatbed would likely beat the GL350 pulling a 7300 lb. boxy toyhauler. My disclaimer is that the steeper the hill gets, the less a factor aerodynamic drag is since speed decreases.
In this 'head to head' are you accounting for those small circumference tires on the SUV, ups the effective torque a fair bit I'd expect...
Tire size; gear ratios and the engine torque curve all need to be considered together.
Say you have a tractor capable of delivering 200 HP to the draw bar. With 6 foot diameter tires you find that in 3rd gear it can travel 2 mph and put 37500 lbs of pull to the draw bar. Now say you get the idea that you can put smaller tires on the tractor and "increase the effective torque" (as you describe it). So you put 3 foot diameter tires on it. Now it puts 75000 lbs of pull to the draw bar in 3rd gear but it is only capable of 1 mph. You bump it up to 6th gear and find you can now go 2 mph and the tractor can deliver 37500 lbs of pull to the drawbar.
