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Sport w/Max Tow - What not to change to maintain payload capacity?

PyrPatriot

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Putting larger tires on the vehicle does NOT change anything with the geometry/angles of the suspension (unless you consider the spare's increased weight increasing the payload). Wheels/tires are not supported by the vehicle suspension, and thus changing their height/weight doesn't cause the vehicle to sag any more or less.
Right, they are not supported by the vehicle. Now that I give it some more thought, I see the height increase comes from the bottom radius of the tire, and that lifts up the center of the wheel itself up, meaning nothing changes with respect to relation between hub/axel and connection to the rest of the vehicle. That would change with a lift kit or spacers, but not just by tires. Thank you for catching the error of my thinking.
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ShadowsPapa

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Putting larger tires on the vehicle does NOT change anything with the geometry/angles of the suspension (unless you consider the spare's increased weight increasing the payload). Wheels/tires are not supported by the vehicle suspension, and thus changing their height/weight doesn't cause the vehicle to sag any more or less.

I do agree that larger/heavier tires does reduce your towing capacity though as they need extra oomph/stopping power to get moving or stopped.
Sag has nothing to do with it.

Payload = GVWR - curb weight
So if that formula is correct, you increase the weight of the wheels and tires, you decrease payload.

This is from Ford - confirming my thinking - (I took some time to verify I was thinking correctly)
---------------------------
PAYLOAD is the combined maximum allowable weight of cargo and passengers that the vehicle is designed to carry.
It is the Gross Vehicle Weight Rating minus the Base Curb Weight.

---------------------------

So if you increase tire weight, you decrease payload because you have increased curb weight.

If each tire is 20 pounds heavier, you have decreased your payload by 80 pounds. Small, but it counts.

There is more leverage on the wheel when applying sideways loads to it so it does impact the capability of bearings, axles, hubs, etc. to deal with the weight. Splitting hairs (as opposed to hares) but still - it's an impact.

You change the gear ratio taking off and the load on the engine.
 

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Sag has nothing to do with it.

Payload = GVWR - curb weight
So if that formula is correct, you increase the weight of the wheels and tires, you decrease payload.

This is from Ford - confirming my thinking - (I took some time to verify I was thinking correctly)
---------------------------
PAYLOAD is the combined maximum allowable weight of cargo and passengers that the vehicle is designed to carry.
It is the Gross Vehicle Weight Rating minus the Base Curb Weight.

---------------------------

So if you increase tire weight, you decrease payload because you have increased curb weight.

If each tire is 20 pounds heavier, you have decreased your payload by 80 pounds. Small, but it counts.

There is more leverage on the wheel when applying sideways loads to it so it does impact the capability of bearings, axles, hubs, etc. to deal with the weight. Splitting hairs (as opposed to hares) but still - it's an impact.

You change the gear ratio taking off and the load on the engine.
Not arguing any of this info, and thanks for sharing. I was just pointing out that suspension geometry itself doesn't change due to tire size.
 

ShadowsPapa

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Not arguing any of this info, and thanks for sharing. I was just pointing out that suspension geometry itself doesn't change due to tire size.
I think I can find a way around that statement - LOL - how many Jeep people put on bigger tires and do NOT lift their Jeep?
HAHA - so, if you are talking about Jeep people, going to bigger tires means it changes because they lift it.
OK, I'm being goofy now - you are right, TIRE size change doesn't change the suspension.
 

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ShadowsPapa

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danielspivey

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Is it possible to put bigger tires and maybe a <=2" lift on a Gladiator Sport w/Max Tow without significantly decreasing its payload or towing capacities? I would like to put on 33" (or maybe 35") tires without compromising its capabilities. Only do light off-roading. Primary use of the vehicle is to haul stuff and to be comfortable on the highway.

If it is possible to increase the tire size, would appreciate any recommendations on specific tires that will have the necessary load and top speed ratings, decent off-road / snow traction, but comfortable and not too loud when driving with the doors and top off. Would also appreciate specific recommendations on what if any changes would need to be made to the suspension that wouldn't cause any decrease in payload or towing capacity, or highway comfort.

Thank you.
I did a LOT of research on this before I finally settled on what I did with my max tow.

Tire wise I went with 285/75r17 wildpeaks, which are close to 34s. To be honest there was no noticeable negative change in throttle response or anything really. I think it actually improved the way it drives, I run around 36 psi in the tires, handles better, steering is better, feels better towing. Tires don’t rub at all, and didn’t have to remove the bumper air dam. I threw on some rubicon take offs, which are the same size as stock rims. The 285/75r17s are the biggest wildpeaks you can legally put on the 7.5 stock rim. I actually prefer the tucked look, versus tires sticking out past the fenders. No issues with flinging you rocks or mud to the body. Only negatives I found were there was about a 1.5 decrease in mpgs and had to calibrate the speedo.

I decided not to go with a lift. A 2 inch mopar looks cool, but I don’t need it. Also it’s like $1300-1800 depending on where you get it and who puts it on.

Suspension wise I haven’t changed anything other than bought a rubicon takeoff suspension ($160). The only thing I put on mine was the Rubi fox shocks, which I think improved the ride and Cornering. If you swap out the springs it’ll lessen the towing and weight capacities I’ve heard.

I also threw on a fox IFP steering stabilizer. I think think this is the best bang for the buck. It definitely improved the stability going over bumps, especially bumps in turns. I never had wander problems, but I would say my steering is now excellent. Tight and no wander.

I’ve put 1600 pounds of flooring in the bed and towed my tritoon which is 7200 Loaded with the trailer. My Jeep does great and holds its own to full size trucks!!

Overall I’m super happy with my set up. Drives great, tows great and looks bigger than a stock rubicon side by side.

The first 3 pictures are without side steps, and the last couple are steps mounted. They are the mopar aluminum ones.. picked them up from a guy for $220 and he helped me put them on in his driveway, which was a killer deal. I will say it looks “bigger” and better without the side steps, but my wife and 5 year old needed them.

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KVJ

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I put 33" tires on my Max Tow with no lift and notice MPG is less both towing and non-towing.
Mine feels better handling too.
 

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Tires and wheels don't change payload. They're unsprung weight. Legally, they don't alter your ratings at all. Practically, they do because they require more engine power and braking power. Having said that, there are LOTS of people who haul and tow with 35" tires on their Jeeps.

If you're concerned about having enough payload remaining to still be able to get the job done, here's my advice:

-Choose tires wisely. The weight of tires changes drastically depending upon tire brand and model. A Falken Wildpeak A/T3W is HEAVY compared to, say, a Goodforayear Wrangler Duratrac of the exact same size. Pick wheels and tires that are lightweight. Some brands are lighter (Goodforayear, Firestone, Cooper, BFG, etc.) and some are notoriously heavy (General, Falken, Toyo, Nitto, etc.).

-Begin with a Sport model. The more payload you start with, the more you'll have remaining after you do your mods. Bonus points if you buy the $995 Max Tow package because then you get wide track axles for better stability, 4.10 gears, more towing capacity, etc.

-Add aluminum accessories wherever possible. And check weights on all accessories. I went with Mopar step rails which saved 50 lbs. per side compared to aftermarket tube steel rails. I did the Quadratec winch bumper which was lighter than the other brands. I switched my winch cable from steel to synthetic and the fairlead from roller to hawse which saved 25 lbs. Every part matters. Shave weight wherever you can.

-Use a spacer lift kit, not a coil lift kit. By using spacers, you are not altering the factory spring rate at all. You can maintain factory performance when hauling and towing.

With all the mods in my signature line, I'm still at 1,300 lbs. of remaining payload which exceeds a stock Overland by a long shot and exceeds a stock Rubicon by 100 lbs.
 

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Bobzdar

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Tires and wheels don't change payload. They're unsprung weight. Legally, they don't alter your ratings at all. Practically, they do because they require more engine power and braking power. Having said that, there are LOTS of people who haul and tow with 35" tires on their Jeeps.

If you're concerned about having enough payload remaining to still be able to get the job done, here's my advice:

-Choose tires wisely. The weight of tires changes drastically depending upon tire brand and model. A Falken Wildpeak A/T3W is HEAVY compared to, say, a Goodforayear Wrangler Duratrac of the exact same size. Pick wheels and tires that are lightweight. Some brands are lighter (Goodforayear, Firestone, Cooper, BFG, etc.) and some are notoriously heavy (General, Falken, Toyo, Nitto, etc.).

-Begin with a Sport model. The more payload you start with, the more you'll have remaining after you do your mods. Bonus points if you buy the $995 Max Tow package because then you get wide track axles for better stability, 4.10 gears, more towing capacity, etc.

-Add aluminum accessories wherever possible. And check weights on all accessories. I went with Mopar step rails which saved 50 lbs. per side compared to aftermarket tube steel rails. I did the Quadratec winch bumper which was lighter than the other brands. I switched my winch cable from steel to synthetic and the fairlead from roller to hawse which saved 25 lbs. Every part matters. Shave weight wherever you can.

-Use a spacer lift kit, not a coil lift kit. By using spacers, you are not altering the factory spring rate at all. You can maintain factory performance when hauling and towing.

With all the mods in my signature line, I'm still at 1,300 lbs. of remaining payload which exceeds a stock Overland by a long shot and exceeds a stock Rubicon by 100 lbs.
Larger wheels and tires affect curb weight, so they do affect payload and towing. If you increase your curb weight, whether it's sprung or not, it decreases your payload and towing as there is no way to increase the gvwr or gcwr. Legally, Payload is gvwr minus curb weight, so if you increase curb weight, payload decreases. No way around that. If you go across the scales over gvwr, whether that weight is in the bed or is due to the wheels/tires, you'll be over weight. Good luck trying to explain that since your wheels and tires weigh 150lbs more than stock, you aren't over weight by 150lbs. They'll laugh at you and write the ticket.
Those larger tires also will alter the efficiency of the drivetrain, so could reduce the gcwr itself (won't matter to gvwr as power/cooling aren't limitations to that) but there's no way to tell by how much without having it recertified, which I doubt anyone will want to pay to do.
 

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You DID see the Ford info I posted - as well as info from other sites basically saying the same thing. GVWR - curb weight = payload.
It's in the books and on the towing sites.
So if you are in an accident, and they see the GVWR is 6,000 pounds and your vehicle weighs 5,000 pounds you had better not be carrying more than 1,000 pounds of people and cargo.

From another site -

The gross vehicle weight rating (GVWR), or gross vehicle mass (GVM) is the maximum operating weight/mass of a vehicle as specified by the manufacturer - including the vehicle's chassis, body, engine, engine fluids, fuel, accessories, driver, passengers and cargo but excluding that of any trailers.

This means if your vehicle is 5,000 curb weight and your GVWR sticker number is 6,000 pounds and you add heavier tires and wheels and increase the vehicle to 5200 pounds, you have decreased payload by 200 because you still must not exceed the 6,000 pounds total weight of the vehicle as shown on a scale.

Payload is the difference between the total weight of your truck - curb weight which is what the whole truck, wheels, tires, oil, antifreeze, gasoline/diesel fuel, weigh and GVWR.
Whatever your truck weighs - put it on a scale and weigh it.
Take that weight from the GVWR sticker number - and that is your payload.

Manufacturers don't take off the wheels and tires to reach curb weight. They are included in curb weight.

Sort of funny - because it's said over and over here that accessories and options take away from payload - yeah, they do - and since tires and wheels change your CURB WEIGHT, they change payload.

Bottom line - and it's stated everywhere, wikipedia, FORD TRUCK payload calculations, and other books and resources -
Payload = GVWR minus CURB WEIGHT.
 

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If you are only going to do "mild off-roading" why even lift at all? It's not necessary - again, as explained in another thread where someone asked what they needed to do...... you really don't need to do anything to take these off-road even in some pretty rough areas.
Almost anything people do with these is for looks. Bigger is more macho. Lift - the higher, the more macho. Doesn't make the Jeep better other than looks, and personal feelings about it.
Lift and large tires are only for extremes. The rest is looks. Unnecessary. I bet with only better tires for traction, even if the same SIZE, I could take my overland where a lot of others here go. Unlifted.
You mention only two types of off-roading: “mild” and “extreme.” I long have done non-“extreme” off-roading where clearance matters.

Your Overland has 10.0 of clearance under the middle of the vehicle. My JTR started out with 11.1” of clearance. With the 35s, it went up to 12.1” of clearance. By Tuesday afternoon, with the 3” RK lift on, it will have around 15” of clearance.

Going over 12” diameter rocks is not “extreme.” I will be doing that in April with some friends and my sons. The place we’re going doesn’t even let you on those (#8-rated) trails if you don’t have, at minimum, 35” tires, some lift, and a winch. They have lesser-rated trails for those who don’t. The trails are challenging but fun with 35” tires and a lift; are impossible with 10” of clearance; and are not “extreme.” The extreme trails (rated ##9-11) are the ones generally occupied by the guys with their extremely-lifted trailered Jeeps or dune buggies.

With my rig, I can go over 12”-14” rocks slowly in 4L, and as long as I don’t run my diffs into them, will clear them without any bonking on my underside.

There are a bunch of public places I will be able to go with the modified JTR, to which I have gone in the past and intend to go in the future, that I would not have been able to go with the stock JTR. If you told any experienced off-roader that these were "extreme," they would roll their eyes.
 

ShadowsPapa

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You mention only two types of off-roading: “mild” and “extreme.” I long have done non-“extreme” off-roading where clearance matters.

Your Overland has 10.0 of clearance under the middle of the vehicle. My JTR started out with 11.1” of clearance. With the 35s, it went up to 12.1” of clearance. By Tuesday afternoon, with the 3” RK lift on, it will have around 15” of clearance.

Going over 12” diameter rocks is not “extreme.” I will be doing that in April with some friends and my sons. The place we’re going doesn’t even let you on those (#8-rated) trails if you don’t have, at minimum, 35” tires, some lift, and a winch. They have lesser-rated trails for those who don’t. The trails are challenging but fun with 35” tires and a lift; are impossible with 10” of clearance; and are not “extreme.” The extreme trails (rated ##9-11) are the ones generally occupied by the guys with their extremely-lifted trailered Jeeps or dune buggies.

With my rig, I can go over 12”-14” rocks slowly in 4L, and as long as I don’t run my diffs into them, will clear them without any bonking on my underside.

There are a bunch of public places I will be able to go with the modified JTR, to which I have gone in the past and intend to go in the future, that I would not have been able to go with the stock JTR. If you told any experienced off-roader that these were "extreme," they would roll their eyes.
Apparently mud trails and river trails here in Iowa are different than where you and others go. I'd be fine with mine. The rocks were buried long ago by the glaciers unless you get to southern Iowa.
On the other hand, I went 4 wheeling with buggies up in Alaska on old logging and mining trails. The ground clearance wasn't all that great in those - but they were trails used by trucks decades ago.
Point taken.
 

maxpower220

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I have never frequented mid size truck forums until I began my pursuit of a Gladiator. I have been a member on the F150 forum for 7 years through ownership of that vehicle. I find A LOT of threads on here concerned about payload and towing, way more than on that site. Way more than I would expect. I'm not sure what the fascination or concern is with this truck. If you are towing at or near the max for the truck; and you are concerned about exceeding the posted limit for your JT, you already know that you should have bought a 1/2 or 3/4 ton truck. Adding this tire size, or lift, or combo of both will change the capacity of the JT (maybe in a manner that is so small you shouldn't be concerned).
ask and you shall receive (does not apply to vehicle applications whatsoever).

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We are now hanging from above? Like some carnival ride?!?!

I can understand that as often as I jump my truck off of ramps and hills, that I may be stretching the springs. I'm willing to accept that.
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