Trucks & Trailers - Lift, bigger tires' effect on tow rating?

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aiian
02-08-2012, 10:26 PM
Strange question, my truck is rated to pull 4.9k pounds. Does my capacity decrease with a lift and off road tires? If so, about how much?

I have a 3" lift/leveling kit and went from the factory 31" tire to 34.5" Nitto TrailGrapplers.

We're looking to buy a Contender 21/23 or Bluewater 2150 before summer and I don't necessarily want to trade in my little Tundra unless I absolutely have to.

Truck in question, because every one loves pics :thumbsup:
http://allangreendale.net/dump/tundra/tht.jpg


2StrokenMako261
02-09-2012, 12:13 AM
Yes and no, It wont have as much power as it would stock, but should be able to pull that.

One reason if you look at stock GM products, they have small tires, thats to increase there payload, where fords stock tire is way taller

MacCTD
02-09-2012, 04:15 AM
Definetly decreases the tow capacity, tough to say by what amount.
Is your truck 2wd with the 4L 6 cyl?


KarlP
02-09-2012, 04:26 AM
Lets assume your truck is a 2007 with over 60k miles. Since your tow rating is a warranty issue, the larger tires will have no impact on your expired warranty when towing. :)

Obviously a higher center of gravity, less braking power, and (unless you regeared) a higher transmission ratio don't improve towing ability.

t500hps
02-09-2012, 05:18 AM
It's not likely to mean much in "tow rating" but you will notice a difference from stock. Braking distance will increase and acceleration will drop due the the extra weight of larger tires. 100lbs in the bed of the truck doesn't make much difference, but 100 lbs of extra tires really does. Since you've already modified the truck and I assume you have a boat, you should have noticed this difference already.

FYI: I did almost your exact mods to a Ford dually. 6.0L 4:10 gears and went from 31.5 to 34.5 tires.......towing a 21 ft CC is obviously not an issue but I did notice the difference after the bigger tires went on. My effective gear ratio dropped and pulling power was lost, braking distance increased as well.

muskamoot
02-09-2012, 07:49 AM
Kills the gearing,makes your truck brakes less effective and screws up the hitch height of the truck.The lift also changes the leverage of the trailer on the truck by altering the angles of various hitch related hardware.

DoubleO7
02-09-2012, 08:25 AM
It's not likely to mean much in "tow rating" but you will notice a difference from stock. Braking distance will increase and acceleration will drop due the the extra weight of larger tires. 100lbs in the bed of the truck doesn't make much difference, but 100 lbs of extra tires really does. Since you've already modified the truck and I assume you have a boat, you should have noticed this difference already.

FYI: I did almost your exact mods to a Ford dually. 6.0L 4:10 gears and went from 31.5 to 34.5 tires.......towing a 21 ft CC is obviously not an issue but I did notice the difference after the bigger tires went on. My effective gear ratio dropped and pulling power was lost, braking distance increased as well.

The increased tire weight increases the flywheel effect.
But it also increases the lever length between the axle and the road of which the brakes have to overcome in order to do a proper job.
That longer lever also makes everything else in the drivetrain work harder.
That lever is 11.3% longer so maybe there is an 11.3% reduction in tow capacity.

maxzilla
02-09-2012, 08:58 AM
My GMC doesnt seem to notice.

http://img821.imageshack.us/img821/6987/boat093.jpg (http://imageshack.us/photo/my-images/821/boat093.jpg/) Uploaded with us (http://imageshack.us)

http://img704.imageshack.us/img704/4188/boat094.jpg (http://imageshack.us/photo/my-images/704/boat094.jpg/) Uploaded with us (http://imageshack.us)

aiian
02-09-2012, 10:17 AM
Yes, it's the 4L V6, RWD.

I figured the capacity would decrease with the modifications but does anyone know by about how much?

I've pulled an 18' SeaPro CC up and down 95 a few times and I didn't exactly feel like the truck was inadequate. She pulled and stopped just fine. I don't know how much the SeaPro weighed but I can't imagine the Contender or Bluewater could bet that much heavier.

jwfost
02-09-2012, 10:28 AM
8" lift and 40" tires and I have no complaints towing my boat, camper, or car trailer

DreamCatcher14
02-09-2012, 10:41 AM
For short trailer rides you should be ok, but you will be working that truck hard at or above its max capacities. Highway speeds will drastically reduce the tranny life.

I would also try and get someone to chime in a a real world weight on a 2150 bluewater with full fuel, gas, ice and dual axle trailer. I think you will be above the 5000lb mark.

Contractor
02-09-2012, 10:50 AM
I'm not sure what the lift or tires do to the towing capacity, but I think that truck would struggle to tow a 21BW/21Contender to begin with.

blackdawg
02-09-2012, 11:34 AM
You didn't go that big but as you sit now with basically just bigger tires and no other significant mods yes you probably lost some capability. You also are stressing your tranny more and the heavier tire is working the stock brakes more. Re-gearing a 4x2 is relatively cheap and can take care of the loss of power up to a point and take the strain off the tranny (use a calculator to figure your stock overall ratio and then what gear is needed to get that back considering the new tire and then go at least one higher numerically), plenty of aftermarket brakes (powerslots/toyota upgrades/wilwood/brembo/etc.) to get that back and then some and with a drop/adjustable ball mount should have no issues getting whatever ball height you want. Aftermarket sway bars, shocks, springs, bags/etc. all avaliable to stabilize and in some cases improve ride over stock when loaded. It's all about what you build your truck to do and doing all the supporting mods to do it right. You didn't go so big in the tire that you can't do some supporting mods to get back whatever capabilities may have been reduced. In the end you can never really get back loss of mpg and the money it all costs to do it.

Gear - $500-600/axle
Brakes - $1,000 for small upgrade and about $4,000 for full 6 piston/slotted system
Suspension mods - couple hundred to several grand

IMO for your truck and what you've done I'd change the gear and put on a set of powerslot rotors and good pads minimum. Also, may want to upgrade the stock shocks to something like Bilstien and consider a set of bags in the rear. Probably $2k total.

crothers
02-09-2012, 12:12 PM
I would calculate your gearing reduction from stock: Same % decrease in gear ratio as is the increase in % of tire diameter. I would then base the tow rating based on he stock truck with your new "effective" gear ratio. There is a catch though, you have diminished brake leverage by the same amount that the stock equivalently geared truck will not see.

Then there are the subleties:
.Did the lift kit come with a new driveshaft and provision to maintain the stock pinion angle(s)?
.Worse aero drag
.Higher center of gravity. Less stable unless widen track which requires a whole bunch more suspension parts. Wheel spacers just task the bearings more.
.More rolling resistance (effective drag) with larger tires. Increase % throttle required at all speeds.
Unless a thoroughly designed complete system (ala Ford Raptor), you likely are sacrificing a lot for "the look". Jeez, remember the days of the early 90's when it was the little 12" wheels spaced out from the body that was "cool".
To the OP: very tasteful, love the monochromatic look.

JOEKEN
02-09-2012, 12:29 PM
I'm not sure what the lift or tires do to the towing capacity, but I think that truck would struggle to tow a 21BW/21Contender to begin with.I towed my 2150 with a 2005 Tacoma that has the same drivetrain. It pulled it great. I now have a 2011 F150 with the 5.0L and don't notice a big dirrerence between the two.

muskamoot
02-10-2012, 06:20 AM
Whatever you do,make sure you readjust the trailer hitch height to level out the trailer.

GatorContender
02-10-2012, 06:48 AM
You will be fine...I tow my 23 contender with a 3" lifted and modded Tacoma with no problems. Of course, towing awareness and proper braking strategies are required as you will be harder to slow down.

Your truck is beefier than mine so I wouldnt hesitate!

http://plaza.ufl.edu/keith3/Contender/Bottom_Paint/IMG_2531.JPG

Jonboater
02-10-2012, 09:44 AM
I towed my 2150 with a 2005 Tacoma that has the same drivetrain. It pulled it great. I now have a 2011 F150 with the 5.0L and don't notice a big dirrerence between the two.

That is an interesting comment. You would think 120+ extra hp and 100+ ft/tq would make a pretty obvious difference.

Patton222
02-12-2012, 02:32 PM
That is an interesting comment. You would think 120+ extra hp and 100+ ft/tq would make a pretty obvious difference.

The ford probably weighs a lot more than the Taco thats why it probably doesn't seem significant.

knotdusty
02-21-2012, 09:29 AM
For every inch in tire diameter you will lose approx. 500lbs in towing. It is always something that has stuck in my mind when I am looking at new tires or rims. Here is a link www.traveledlanetrailers.com/trailering101/trailering5.htm . It should also say something in your owners manual.

DoubleO7
02-21-2012, 11:16 AM
I towed my 2150 with a 2005 Tacoma that has the same drivetrain. It pulled it great. I now have a 2011 F150 with the 5.0L and don't notice a big dirrerence between the two.

That is an interesting comment. You would think 120+ extra hp and 100+ ft/tq would make a pretty obvious difference.

The ford probably weighs a lot more than the Taco thats why it probably doesn't seem significant.

If the transmission and rear end gearing are not optimum to go along with more HP and torque, there might not be any significant differences in towing performance.

condore
04-12-2014, 10:43 PM
It might be fine to tow something light when you have a lift kit and big tires. It is not advisable to tow heavier trailers at highway speeds 55+ with this type of set up. It may be fine for off road but the high center of gravity and the large amount of flex in the large tires is a recipe for disaster when towing. My son learned this lesson the hard way. This was the result towing a 21ft Regal.

Dantilu
04-13-2014, 05:36 AM
Just a thought …. could you move up in tire rating? I know for Diesel 3/4 ton we should run an E rated tire for weight….. could you move up on weight rating for safety ???

LouC
04-13-2014, 10:44 AM
I agree with the last poster, the only thing larger tires does for you is add clearance for off road. If you need that fine but if not you are making all performance variables worse (slower, less hill climbing ability, worse braking and rougher ride). Compare the weight of those vs OE, I bet they weigh much more and 3" in height is a lot.
I looked into going to bigger tires for my 07 jeep but decided it was not worth the compromises (36 lbs vs almost 50).
Since I only off road on beaches I don't need more clearance and properly aired down standard size tires do fine on the beach.

Most tire retailers recommend staying within 3% of the original circumference.

While sometimes you can go from a P to a C or D rated tire they need more air than the original P pressure.



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