Hello,
Well I'm the guy who had his truck at the dealer for 3 weeks with a dead ECM amd FCM. Probably unrelated to this gripe but here goes. I have a 24ft Keystone Sprinter TT maybe 8000 wet. My truck is auto, 35's with 3.73. I could not pull any of the grades/passes here in Washington State on I-90/H 26 over 50 mph. This is my first travel trailer towing. I have a 20ft boat that weighs around 3800 and pulled it numerous times with my 03 6-spd with 3.73's at 70 all day any pass or grade. Is this normal? Is it the 3.73's? Do all of you have a hard time towing TT/FW's? Thanks in advance. I was very upset I couldn't go the speed limit the whole way with my 48K truck.

 

That seems a little slow to me but maybe the autos loose that much power. I dont know. I have a six speed and have pulled this threw the Colorado mountains at 70+mph with no real problem. The grades where 8-10% for up to 8 miles and it would pull it at 2700-2800 RPM in 5th gear. Like I said it seems a little slow to me but it may just be dodge's worthless auto wasting that much power. I dont know.

 

Ok I have at setup like your but it is an 04.5 with the 3.73 and 35's and have not towed with it yet since I upgraded to the 35's. I will be honest and say I do not know what degree a grade is, but I will be towing my boat, a little over 5,000 pounds, this week up a few grades and I will let you know how it does.

 

i don't know about the 48re but nice truck. 47re auto is garbage though. so is the nv4500 though, or is it nv5400?? well i'll be, i forgot.

 

Thanks. I just expected a lot more power. I think I should have went with the 4.10's. I thought the auto's came with it but found out I was wrong after the purchase. Thanks again.

 

I have an 04 auto and also a 6spd. There is no way I could pull a backhoe or dozer up an 8 mile grade like that in the auto. Period
Maybe if I kept it in 2nd and did 35-40 screaming.

But the 6spd pulls it all day long and so does the Powerstroke with auto.

The only thing this 48RE gives me is no shifting and once you get up to 70 it cruises nicely but I'm in Texas, we don't have grades. A simple hill knocks me back to 48mph and 2800 rpm is where I hold.

 

Sounds like it is normal then. How much would a Superchips help? I hate to void my warranty though. Thanks for the reply. Take care.

Rick

 

When you increase your tire diameter, you decrease your effective mechanical advantage with the rear end ratio. You may have gone from a 3:73 ratio to a 2:91 ratio with the tire size. That will reduce your power in higher gears.

There is a web site, that I no longer have due to HP wiping my hard dirve during service, that will allow you to enter you tire size and your ratio and give you your actual rear ratio with your tires.

I will repost the site if I can find it. Maybe someone else has it handy.

Dave

 

Don't have the website but consider this: Going from the stock 265/70-17 tires which are about 31.5" to a 35" tire is an increase of about 3.5 inches in diameter. That would give you a decrease in mechanical advantage of approximately 11%, that's 3.5 inches divided by 31.5 inches. Actually you need to divide the tire diameters in half and do the calculations based on radius, but you still end up with approximately 11% decrease.

BTW this is not only a negative impact on "Go" power it also impacts stopping power.

 

the main diff. I see is that you are now pushing a lot more wind with a travel trailer, than a boat unless the boat is a really tall #3800 boat. wind is a big factor in milage as well.

 

it is your gears

i have the 05 3500 drw with the 3.73s and the auto and stock tires

i have a 26 ft fiver that i flat tow my jeep behind 12k lbs of trailer and jeep

i have no problem towing in colorado 5-9 percent grades

 

On my 04.5 2500 4x4 3.73 auto with 285/70/17s my experiance is similar to Rockhounds with a slightly different but comparable load. It seems like any thing above 285s and there is a noticable loss in towing performance.
Joe

 

Thanks for the replies guys. I feel a little better.

 

I pull a Mountaineer TT coming in close to 11K lbs when fully loaded. My truck (see signature) has 3.73 rear and I am still running the orgininal 265/70/17 tires (havent wore out yet). I have towed throughout NC mountains and there was not one grade that slowed me down. I kept the truck set on cruise and it pretty much stayed right at 70 not even being phased by any of the grades. There is on climb one I think I-24(?) headed towards Nashville outside of MontEagle TN that slowed me down to around 60 - 65-ish but man everyone else was like they were standing still.

 

You can do the calculations based on diameter OR radius. Either way, the important number is the circumference which is a one-dimensional (linear) value. So are the diameter and the radius, so it doesn't matter which one you use.

C = 2 * R * pi

Since 2R is the same as diameter:

C = D * pi

...so C is directly proportional to D. In other words, for rough calculations the circumference is ~3X the diameter. You can do your comparisons using C, R, or D.