Questions on towing with a lifted truck

[Powts]

First off, this is such a great site. I did a ton of reading and research and it totally Influenced me to go out and buy a brand new GMC 3500HD and a 35ft travel trailer. I've never owned or even towed a trailer! Took delivery in October and got one quick trip in up to Whistler with the family and it was such an incredible experience. Thanks for all the great info.

Now that I've had the truck for a few months I'm tossing around the idea of adding a few toys. A proper 4" suspension lift is on the list. Other than the obvious hit to fuel economy and practicality, is there anything inherently wrong/dangerous about towing with a lifted truck? The particular lift I'm looking at doesn't change the CV angles much past stock ride height and I can purchase a drop hitch to keep hitch height the same as the stock height now. The lift also doesn't chnage the stock rake of the truck. Any help/thoughts/feedback/ideas welcome. Thanks in advance!

[mudfuel07]

milo wrote:

mudfuel07 wrote:

milo wrote:
Quote... what the purpose of lifting a truck is. :h

Looks cool having to put a 4' ladder out for the wife so she can get in & out of the truck. :C

You must not like your wife!!:h For me, it means I get a little action helping her up and down--it's a nice side benefit!

Hmmmmmm... Why would I not like my wife if you have to put a ladder out to get your wife out of your truck. :h Guess for you that kinda action is better than no action at all huh......LMAO

Wow, you're old and using teenage slang. Good comeback. It was meant as a joke, but it must have gone above your head.

[milo]

mudfuel07 wrote:

milo wrote:
Quote... what the purpose of lifting a truck is. :h

Looks cool having to put a 4' ladder out for the wife so she can get in & out of the truck. :C

You must not like your wife!!:h For me, it means I get a little action helping her up and down--it's a nice side benefit!

Hmmmmmm... Why would I not like my wife if you have to put a ladder out to get your wife out of your truck. :h Guess for you that kinda action is better than no action at all huh......LMAO

[BenK]

My 1996 8.6K GVWR TV with over sized tires can still go into parking garages
that many of the +7K GVWR half ton TV's CAN NOT enter because the OEMs understand
how their buyers want taller trucks with the same ratings of older, but same GVWR's

[mudfuel07]

milo wrote:
Quote... what the purpose of lifting a truck is. :h

Looks cool having to put a 4' ladder out for the wife so she can get in & out of the truck. :C

You must not like your wife!!:h For me, it means I get a little action helping her up and down--it's a nice side benefit!

[milo]

Quote... what the purpose of lifting a truck is. :h

Looks cool having to put a 4' ladder out for the wife so she can get in & out of the truck. :C

[mudfuel07]

Wow! Lift it and enjoy it. The height you're going to will make little difference. I assume that you are putting on a quality kit, so there shouldn't be a problem. My current truck is the first non-lifted truck that I have towed with and I have never experienced a bad tow from mild 3" lift to a 8" lift. As long as you, the driver, takes into account everything, you'll be good. A 4" on a GM isn't that much. I'm in the camp that if it makes you happy, that's all that matters!

[BenK]

The most accurate for tire vs diff ratio is to use the tires "rev's per mile"

Even if the tuner asks for the tire dia...there is a look up table that it then
converts to "rev's per mile"...as the ECU counts the number of rev's over a time
frame to determine the speed

[Bedlam]

From stock GM tires (about 31") to 35" you are looking at about a 11% overdrive from stock gearing. If you are close to your towing limits, this may make a difference. My Ford came with tires ranging 31-33" tall. When I bought it, I had the shorter tires and went to the taller ones after they wore. Although My tow rating did not change, I could tell the difference in the shift points when I towed my 11K+ lb trailer through the mountains. Where I was holding a particular gear, the 6% overdrive now had the transmission downshift one gear lower. I did see a slight rise in unloaded highway mileage with the taller tires, but towing was the same. In my case, the change to a slightly taller tire was not detrimental to mileage but it did make the engine and transmission work more.

[BurbMan]

Ummm...OK...I see that math was not your strongest subject. Let me see if I can clarify.

majorgator wrote:
You referred to the tire WIDTH and referenced that as the tire HEIGHT. The second number in this method of tire sizing gives reference to the height. I never said anything about gear changes.

You are correct, the 245, 265, 285, etc, refer to the width of the tire in millimeters. The second number, the "75", is the aspect ratio, which is the ratio of height to width. So, if you increase the width and keep the aspect ratio the same, the diameter of the tire will increase too. Sorry if I wasn't clear on that.

majorgator wrote:
The calculator you linked to is not accurate. It depends on linear data input and provides linear data outputs. As stock tire size increases, the calculator becomes less accurate, because overall diameter increases become less of a factor. If you increase the diameter of a compact car tire by 2", then you've made a huge change. But when you increase a large heavy duty tire diameter by 2", you've created an almost negligible impact. A straight-line calculator cannot deal with this.

The calculator that I linked to is 100% accurate. You are correct that it is linear, because geometry is linear. If you increase the diameter of a tire by 2" it will have the exact same effect on the gear ratio on any vehicle, whether it is a large truck or a mini cooper. It would be a smaller % change on the large truck, but the numerical change is the same.

majorgator wrote:
Don't be so quick to justify yourself that you fail to read.

I don't need to justify myself, it's just math is all. Sorry if you don't get it.

The FACT is, you reduced your towing power with those taller tires on your truck...but if you are satisfied with how it drives, that's all that matters...it's your truck not mine.

I only posted this info so that the OP could take this into account when lifting the truck he uses to tow a 35' trailer.

[majorgator]

BurbMan wrote:

majorgator wrote:

BurbMan wrote:
Also be aware that taller tires will effectively decrease your axle ratio. Formula is the old tire diameter divided by the new tire diameter times the axle ratio. For example, I have 4.10's on my truck, and when I swapped out the factory 245's for 265's, the larger diameter tires reduced my axle ratio to an effective 3.92. I noticed it right away in that the trans wanted to downshift a little sooner on hills, and that's towing 8500 lbs. I wanted a little more ground clearance and traction off road, but didn't go to 285's because I didn't want to decrease highway towing performance that much. So the 265's were a good compromise for me. If I was hiway all the time I would have stayed with the OEM 245's. If I was offroad more of the time, I would have gone with 285's.

The tire size you're referencing is the width, not the height.
FWIW, on my '07 Silverado 1500, I went from 245/70 (stock size) tires to 285/70 tires at my first tire change. The truck improved in every way. Better mileage, better handling, better ride, etc. Nothing changed regarding shifting. The speedo is off by about 3 MPH when it reads 75 MPH. Below that, its negligible.

Absolutely INCORRECT. Overall tire diameter is what affects the rear axle ratio, the width has got nothing to do with that. Do some homework, maybe start here.

Look at Michelin LTX/MS as an example. LT245/75-16 has an overall diameter of 30.5". The same tire in LT285/75-16 has an overall diameter of 32.8". So if you had 4.10 gears in your truck, your new effective axle ratio with the taller tires is 3.81. To maintain the same pulling power with the taller tires, you would need to re-gear to 4.41's...in the GM world 4.56 would be closest.

Fact is, you have reduced the pulling power of your truck with those taller tires. You won't notice it empty, and if you haven't noticed it towing, then your trailer isn't very heavy. Of course in FL your biggest hill is an interstate overpass...

Dude, come on, read my post again. What I said is absolutely CORRECT. You referred to the tire WIDTH and referenced that as the tire HEIGHT. The second number in this method of tire sizing gives reference to the height. I never said anything about gear changes. Don't be so quick to justify yourself that you fail to read.

I'll stick with what I said about my truck. With over 200K miles on it, mixed with highway driving and towing of up to about 6K or 7K pounds, I beleive I can be an accurate judge of its performance. The calculator you linked to is not accurate. It depends on linear data input and provides linear data outputs. As stock tire size increases, the calculator becomes less accurate, because overall diameter increases become less of a factor. If you increase the diameter of a compact car tire by 2", then you've made a huge change. But when you increase a large heavy duty tire diameter by 2", you've created an almost negligible impact. A straight-line calculator cannot deal with this.

[RoyJ]

discovery4us wrote:
Yes you can tow with a lifted truck. All but one of my trucks have been lifted and I have towed with everyone of them, heck my truck camper was on a lifted truck with a trailer behind it. Much of my early camping involved sand and river beds so the larger wider tire was necessary for the added float of the tire.
I have always stayed with four to six inch lifts and around a 35 X 12.50 tire and always felt safe and in control from my tent trailer to my 40' FW TH. If you don't already have in the neighborhood of 4.10:1 gears you may find a need to regear and depending on the trailer height you may need to consider flipping the trailer axles.
From my experience I wouldn't hesitate to tow with a lift and larger tires. My current chevy is a 2004 and even with a 4" lift and 35" tires I am still the same ride height as a stock Dodge 4x4:M

No one said you CANNOT tow with a lifted truck; but there's a difference between "can" and "ideal".

Hard to define safety by feel. We always feel safe, until something happens. I never feel unsafe at 150 mph in my Z06, but is it ideal? No. But it's a risk I'm willing to take. Same with towing with a lifted truck.

The ideal towing setup would be a 2wd regular cab dually, giving the lowest curb weight, lowest COG, highest payload, and the lateral stiffness of a dually. But unless you're hotshot hauling, that's a bit too extreme.

Again, if you have a legit reason for the lift, then don't let towing stop you. Just try to select a lift kit without compromising hauling and towing too much. But if you have a dedicated towing rig and is lifting solely for looks, then I'd highly recommend against it.

[RoyJ]

DirtyOil wrote:
You said it... "Blocks create a large reaction moment..." " this moment twist the leafs" ....nothing about stock vs blocks. Your post suggests that wheel hop only happens to lifted trucks using blocks, it can happen to stock as well as lifted trucks...its not a lift only issue!

Fair enough; let me re-phrase that then:

lifting blocks will magnify any inherent weakness of the rear drive-train design. It'll make any existing condition worse, and possibly create new conditions that didn't exist before.

Lifting blocks does not make ANY performance aspect of the truck better, other than the sole purpose of gaining height, which I do not define as a performance metric. If height is desire, then I'd suggest obtaining that via custom leafs.

[hawkeye-08]

Powts wrote:

VintageRacer wrote:
Everyone knows the obvious drawbacks to lifted trucks, and many with 3500's actually look to lower them for towing, so I won't go there. Once you get the lift sorted the way you want it, you need to fully and completely adjust the weight distributing hitch. You may need to find a real high quality dropped hitch head, mine is adjusted to it's lowest point to fit my stock height F250 so a 4" lift on a 3500 is probably 6" or more difference to mine. As said, watch the weight ratings on the tires and wheels so you get ones that match your usage.

Other than that, it's going to handle a bit worse, brake worse, and probably ride worse so adjust your driving style. Lots of people tow with lifted trucks and do just fine, you probably will too.

Brian

Good points, thanks for this. Tires are the Goodyear Wrangler Duratracs. E ply with a load rating of 126. Should be fine with that as they're a step up in all categories from the OEM's. I'll shop around for a quality hitch head - any suggestions on what/where to buy?

Replace receiver on truck with Torklift SuperHitch Magnum, Torklift adjustable shank with double stinger, Reese Trunnion Bar WDH.

The receiver is good for 20,000lb weight carrying, 30,000lb weight distributing, the shank good for 20,000lbs. Even if you derate it when using it in the drop position, it is still stout enough to handle most travel trailers.

[BurbMan]

majorgator wrote:

BurbMan wrote:
Also be aware that taller tires will effectively decrease your axle ratio. Formula is the old tire diameter divided by the new tire diameter times the axle ratio. For example, I have 4.10's on my truck, and when I swapped out the factory 245's for 265's, the larger diameter tires reduced my axle ratio to an effective 3.92. I noticed it right away in that the trans wanted to downshift a little sooner on hills, and that's towing 8500 lbs. I wanted a little more ground clearance and traction off road, but didn't go to 285's because I didn't want to decrease highway towing performance that much. So the 265's were a good compromise for me. If I was hiway all the time I would have stayed with the OEM 245's. If I was offroad more of the time, I would have gone with 285's.

The tire size you're referencing is the width, not the height.
FWIW, on my '07 Silverado 1500, I went from 245/70 (stock size) tires to 285/70 tires at my first tire change. The truck improved in every way. Better mileage, better handling, better ride, etc. Nothing changed regarding shifting. The speedo is off by about 3 MPH when it reads 75 MPH. Below that, its negligible.

Absolutely INCORRECT. Overall tire diameter is what affects the rear axle ratio, the width has got nothing to do with that. Do some homework, maybe start here.

Look at Michelin LTX/MS as an example. LT245/75-16 has an overall diameter of 30.5". The same tire in LT285/75-16 has an overall diameter of 32.8". So if you had 4.10 gears in your truck, your new effective axle ratio with the taller tires is 3.81. To maintain the same pulling power with the taller tires, you would need to re-gear to 4.41's...in the GM world 4.56 would be closest.

Fact is, you have reduced the pulling power of your truck with those taller tires. You won't notice it empty, and if you haven't noticed it towing, then your trailer isn't very heavy. Of course in FL your biggest hill is an interstate overpass...