Rearend ratio and towing
#16
09-19-2008 | 09:25 AM
Senior Member
Joined: Oct 2002
Posts: 5,358
Likes: 1
From: Commerce Twp, MI
Gearing is the single best change we can do to improve towing power. The problem for 4WD is that it costs $1200-1500. 3.55->3.73 is not worth it. 4.10 would be good, 4.56 would be outstanding! The cheapest way to improve gearing is reduce tire sieze, but as glc mentioned, you need to be careful with load ratings.
What tires do you have, P rated or LT and what size?
Oh, I don't think a 29' Terry RV wieghs 4500 pounds, and your engine/vehicle speed tends to back that up. I recommend finding a scale to find out how much weight is on each of your truck's axles. Your best upgrade may be a Superduty V10.
What tires do you have, P rated or LT and what size?
Oh, I don't think a 29' Terry RV wieghs 4500 pounds, and your engine/vehicle speed tends to back that up. I recommend finding a scale to find out how much weight is on each of your truck's axles. Your best upgrade may be a Superduty V10.
Last edited by APT; 09-19-2008 at 09:30 AM.
#17
09-19-2008 | 02:20 PM
Senior Member
Joined: Mar 2001
Posts: 4,506
Likes: 6
From: Puyallup, WA
Well, I suspect after 7 years, he's probably done something by now! ha, ha!
Wow, that's bringing up an old post there Don292!!
Hey, at least you used the 'search' feature, so we can't fault you there!
Might have been better to just start a new thread, but hey, welcome to the site and hope you stick around for awhile!
It's hard to find LT rated tires in the smaller sizes these days.. While I think the load ratings on the OEM P235/70/16's that my truck came with would handle my trucks GVWR and probably even it's rear GAWR but, I sure didn't like the handling of them on an empty truck! I even went to some P255/70/16's right after I bought the truck and only kept them for a month before trading them in on the LT265/75/16 tire size I run now... Oh, I have so much better unloaded and loaded handling now! I even had to add some overload springs to get the truck to be able to haul anything to begin with!
Now, my F150 is a decent hauler and tower, and that's still with the stock 3.55 gears.. I did have to recal the speedo gear after going to the 265's, but if I need to run in 3rd to haul the load, then I'm only pulling 2400 rpms doing 60 mph, so no big deal... It'll do it all day long and is right in the engines power band at that rpm anyway, so even if I had 4.10's or even 4.56's and towing in OD, I'd only be pulling 1900 rpms w/ 4.10's and 2100 rpms w/ 4.56's, which would still be basically 'bogging' down the engine under a load....
Plus, I'd be pulling those same rpms with those gears in OD towing or hauling absolutely nothing!! Since I only tow about 10% of the total miles I drive a year, I'd rather be able to run in OD with the 3.55's and pull only 1600 rpms running empty 90% of the time. I can actually hold OD for some time on the flats towing my trailer, but for the most part, I just let her run in 3rd.
I guess it's all relative, in that if I had 4.56 gears with only 31" tall tires, I could run in OD on the flats and probably make the grades in 3rd..... Well, without spending all that money and break in time, ect, I can basically do the same thing running in 3rd and 2nd right now, and actually have a better overall gear ratio that matches my engines power band in those gears doing it! Sure, I'm pulling more rpms in 2nd and 3rd with the 3.55's then I would be with 4.56 gears in 3rd and OD, but I'll bet I have better throttle response when I'm running in 3rd and pulling 2400 rpms then in OD pulling 2100 rpms..
If all my truck did was tow a trailer, or haul stuff, then hell yeah, I'd get the lower gears... But to only satisfy 10% of my total driving right now??? It's just not worth it, to me...
Your opinions may vary, but that's my take on it!
Mitch
Wow, that's bringing up an old post there Don292!!
Hey, at least you used the 'search' feature, so we can't fault you there!
Might have been better to just start a new thread, but hey, welcome to the site and hope you stick around for awhile!
It's hard to find LT rated tires in the smaller sizes these days.. While I think the load ratings on the OEM P235/70/16's that my truck came with would handle my trucks GVWR and probably even it's rear GAWR but, I sure didn't like the handling of them on an empty truck! I even went to some P255/70/16's right after I bought the truck and only kept them for a month before trading them in on the LT265/75/16 tire size I run now... Oh, I have so much better unloaded and loaded handling now! I even had to add some overload springs to get the truck to be able to haul anything to begin with!
Now, my F150 is a decent hauler and tower, and that's still with the stock 3.55 gears.. I did have to recal the speedo gear after going to the 265's, but if I need to run in 3rd to haul the load, then I'm only pulling 2400 rpms doing 60 mph, so no big deal... It'll do it all day long and is right in the engines power band at that rpm anyway, so even if I had 4.10's or even 4.56's and towing in OD, I'd only be pulling 1900 rpms w/ 4.10's and 2100 rpms w/ 4.56's, which would still be basically 'bogging' down the engine under a load....
Plus, I'd be pulling those same rpms with those gears in OD towing or hauling absolutely nothing!! Since I only tow about 10% of the total miles I drive a year, I'd rather be able to run in OD with the 3.55's and pull only 1600 rpms running empty 90% of the time. I can actually hold OD for some time on the flats towing my trailer, but for the most part, I just let her run in 3rd.
I guess it's all relative, in that if I had 4.56 gears with only 31" tall tires, I could run in OD on the flats and probably make the grades in 3rd..... Well, without spending all that money and break in time, ect, I can basically do the same thing running in 3rd and 2nd right now, and actually have a better overall gear ratio that matches my engines power band in those gears doing it! Sure, I'm pulling more rpms in 2nd and 3rd with the 3.55's then I would be with 4.56 gears in 3rd and OD, but I'll bet I have better throttle response when I'm running in 3rd and pulling 2400 rpms then in OD pulling 2100 rpms..
If all my truck did was tow a trailer, or haul stuff, then hell yeah, I'd get the lower gears... But to only satisfy 10% of my total driving right now??? It's just not worth it, to me...
Your opinions may vary, but that's my take on it!
Mitch
#18
09-19-2008 | 02:45 PM
Senior Member
Joined: Mar 2005
Posts: 5,843
Likes: 0
From: St. Charles, MO
What the other posters said about tire size is important. Here's a link to a Tire Size Calculator that's fun to play with.
http://www.powerdog.com/tiresize.cgi
List the various tire sizes in the box:
Example.
265/70-17
235/70R16 ....click on Compute Sizes.
The first listed tire size is charted for 60MPH. In this case, the difference for the smaller tire is -8.4%. The diameter of the large tire is 31.6" versus the smaller 29" tire (OEM for my 2003 F150.
It would be interesting to hear from someone who has actually downsized tires for the purpose of towing.
http://www.powerdog.com/tiresize.cgi
List the various tire sizes in the box:
Example.
265/70-17
235/70R16 ....click on Compute Sizes.
The first listed tire size is charted for 60MPH. In this case, the difference for the smaller tire is -8.4%. The diameter of the large tire is 31.6" versus the smaller 29" tire (OEM for my 2003 F150.
It would be interesting to hear from someone who has actually downsized tires for the purpose of towing.
