Question about tires, lifts and gearing

[JPJ987]

Hi All! Im new to the forum, thanks for having me. Recently went out looking for a used Jeep and came home with a 2022 Gladiator Sport Altitude. Wasn't interested initially, then came across a good deal on a low mileage one, drove it and I really love it. It's got the 3.6L motor, stock tires, 8 speed automatic tranny and stock rear end. Iv'e owned two other Wranglers in the past, but this is a little different and getting all different information on the internet. I stumbled on this forum and you folks have some really nice builds, so I figured it best to ask you these questions. Im getting older, not off roading anymore really but I love the look. I'm gonna do a nice mud terrain tire, and what I would like are 35 x 12.5 x 17s, and I was hoping I can just do a 2.5 inch spacer kit to not make it too high because I'm a plumber and I tow a trailer, so I'd rather keep the height moderate. My concerns are rubbing, am I going to lose a lot of power going from a 31 to a 35, and would I need to change then rear end gears? I love the truck, and I would appreciate your input and suggestions. Thanks!

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[Hootbro]

You are going to loose a lot of power and towing capacity going to 35's on the factory 3.73 gears. You will almost never see 8th gear. You could squeak by with 4.10's but most will tell you 4.56 gears will be needed.

Also, putting in that large of a spacer lift up front and also towing, you are going to be looking at some serious rear end sagging. Need to looking at a full spring based lift with correct shocks, sway bar end links, track bats and extend front lower control arms. Spacer lifts suck when it come to ride quality also. There is no free lunch here.

Everything is a compromise when lifting and installing larger tires and maintaining towing capability.

If you are looking to make this a work vehicle, I would leave it stock.

Coming from Wranglers, you should know most of this.

 

[Bigcatfish]

Hi All! Im new to the forum, thanks for having me. Recently went out looking for a used Jeep and came home with a 2022 Gladiator Sport Altitude. Wasn't interested initially, then came across a good deal on a low mileage one, drove it and I really love it. It's got the 3.6L motor, stock tires, 8 speed automatic tranny and stock rear end. Iv'e owned two other Wranglers in the past, but this is a little different and getting all different information on the internet. I stumbled on this forum and you folks have some really nice builds, so I figured it best to ask you these questions. Im getting older, not off roading anymore really but I love the look. I'm gonna do a nice mud terrain tire, and what I would like are 35 x 12.5 x 17s, and I was hoping I can just do a 2.5 inch spacer kit to not make it too high because I'm a plumber and I tow a trailer, so I'd rather keep the height moderate. My concerns are rubbing, am I going to lose a lot of power going from a 31 to a 35, and would I need to change then rear end gears? I love the truck, and I would appreciate your input and suggestions. Thanks!

I have a buddy that says you need to do something with the programming if you lift your jeep. Is this accurate?

 

[1550jrit]

I have a buddy that says you need to do something with the programming if you lift your jeep. Is this accurate?

You can either get a Jscan tool or a Tazer to reprogram the correct tire size and gear ratio. It’s not a big deal at all; both are low cost solutions compared to the regear and tires. I’m fairly certain yhe ship you choose for the regear can add that in as well.

 

[JPJ987]

You are going to loose a lot of power and towing capacity going to 35's on the factory 3.73 gears. You will almost never see 8th gear. You could squeak by with 4.10's but most will tell you 4.56 gears will be needed.

Also, putting in that large of a spacer lift up front and also towing, you are going to be looking at some serious rear end sagging. Need to looking at a full spring based lift with correct shocks, sway bar end links, track bats and extend front lower control arms. Spacer lifts suck when it come to ride quality also. There is no free lunch here.

Everything is a compromise when lifting and installing larger tires and maintaining towing capability.

If you are looking to make this a work vehicle, I would leave it stock.

Coming from Wranglers, you should know most of this.

Thanks for your response, appreciated. Yeah, you are confirming some of which I suspected. And no, my Ram went into the shop for a tranny repair, so I was just using this as a backup. So I won't be making this into a work truck. Jeep says I can go up to a 33" tire without modifications so I can keep the suspension as is, so I'm wondering if I were to use offset rims or spacers I could at least go wider to make it look beefier. Do you think that a 33" tire would still hurt me that bad with power loss?

 

[Hootbro]

Do you think that a 33" tire would still hurt me that bad with power loss?

33" is doable with 3.73 gearing.

 

[JPJ987]

33" is doable with 3.73 gearing.

Thank you, I'll start looking in that direction

 

[Panthers65]

33" is doable with 3.73 gearing.

Thank you, I'll start looking in that direction

Depends on what your doing with it. I've seen people on 39's and stock gears, so "doable" is subjective. If you are planning on pulling a trailer, if you live in a mountainous area, or if you just really like to drive a vehicle that doesn't feel like a 80's 1-ton diesel, you'll still hate the 35's and 3.73

Will it cause your jeep to instantaneously blow up as soon as you touch the throttle? No, but you'll be left with something you really don't like driving anymore.

Where do you live? How big is the trailer you'll be pulling? How much of your time is spent on the interstate vs 45mph around town roads? All that plays into what gears, but as a rule I'd almost ALWAYS recommend overgearing a Jeep. You're already driving a brick on wheels, there is nothing you can do to get better MPGs at 75+mph, you might as well overgear and enjoy the extra torque during towing and around town driving.

I run 5.13's and 37's and love it. I do drive about 7 miles on interstate every day on my way to work, I can run 75-80 no problems at all, I'm just going to get 14-15 MPGs while doing it. If I stick around town or keep it around 65 on the interstate I can regularly average 17.5-18. I also have a 5K lb deckboat I pull and I can actually get on the interstate and run with the 18-wheelers instead of getting blown past them like I was when I was on 4.10's.

on 35's and using your Gladiator anyway like a truck should be used, I'm going to guarantee you'll be happier with 4.88's vs 4.56's. Gears don't really change in price depending on the ratio, they're all the same.

 

[JPJ987]

Depends on what your doing with it. I've seen people on 39's and stock gears, so "doable" is subjective. If you are planning on pulling a trailer, if you live in a mountainous area, or if you just really like to drive a vehicle that doesn't feel like a 80's 1-ton diesel, you'll still hate the 35's and 3.73

Will it cause your jeep to instantaneously blow up as soon as you touch the throttle? No, but you'll be left with something you really don't like driving anymore.

Where do you live? How big is the trailer you'll be pulling? How much of your time is spent on the interstate vs 45mph around town roads? All that plays into what gears, but as a rule I'd almost ALWAYS recommend overgearing a Jeep. You're already driving a brick on wheels, there is nothing you can do to get better MPGs at 75+mph, you might as well overgear and enjoy the extra torque during towing and around town driving.

I run 5.13's and 37's and love it. I do drive about 7 miles on interstate every day on my way to work, I can run 75-80 no problems at all, I'm just going to get 14-15 MPGs while doing it. If I stick around town or keep it around 65 on the interstate I can regularly average 17.5-18. I also have a 5K lb deckboat I pull and I can actually get on the interstate and run with the 18-wheelers instead of getting blown past them like I was when I was on 4.10's.

on 35's and using your Gladiator anyway like a truck should be used, I'm going to guarantee you'll be happier with 4.88's vs 4.56's. Gears don't really change in price depending on the ratio, they're all the same.

Thank you for writing, that's great info. The problem is for me, and I admit, my prior Jeeps have only had a 33" tire with no lift. So the process of creating this build is unknown for me. To answer your questions, where I live & drive is completely flat and straight here in Georgia, I haven't seen a mountain or rock since I moved here. The trailer is an occasional pull when my trucks in the shop, backup, so I want to be a fun truck not a work truck. The trailer is a 6 x 10 single axle utility, about 3000lbs with the tools. Im a semi retired plumber, stay pretty local with very few long commutes and when I do its about 1-2 hour drives on long straight flat roads 65-70mph. I am not concerned about gas mileage, I want to enjoy the vehicle. I know I said 35s, only to use as a starting point because I don't know what's possible. Ultimately if possible, I would love to do 37x12.5x17, tire pushed out past the fender flare a bit, lift kit and re gear (over gear would be better as you suggested). Bottom line, this is super clean and a blank canvas with 65,000 on it, if I can get it to 37s and do it right I would be thrilled. I would appreciate your opinions on this, thx!

 

[Panthers65]

Thank you for writing, that's great info. The problem is for me, and I admit, my prior Jeeps have only had a 33" tire with no lift. So the process of creating this build is unknown for me. To answer your questions, where I live & drive is completely flat and straight here in Georgia, I haven't seen a mountain or rock since I moved here. The trailer is an occasional pull when my trucks in the shop, backup, so I want to be a fun truck not a work truck. The trailer is a 6 x 10 single axle utility, about 3000lbs with the tools. Im a semi retired plumber, stay pretty local with very few long commutes and when I do its about 1-2 hour drives on long straight flat roads 65-70mph. I am not concerned about gas mileage, I want to enjoy the vehicle. I know I said 35s, only to use as a starting point because I don't know what's possible. Ultimately if possible, I would love to do 37x12.5x17, tire pushed out past the fender flare a bit, lift kit and re gear (over gear would be better as you suggested). Bottom line, this is super clean and a blank canvas with 65,000 on it, if I can get it to 37s and do it right I would be thrilled. I would appreciate your opinions on this, thx!

I live in GA too, east of Atlanta. Do you intend to wheel any? I know you say you haven't seen a mountain or rock recently, but driving through the N. GA mountains is one of the biggest benefits of owning a capable Jeep. Not about abusing or bashing to Jeep, but the forest and service roads running all through N. GA are beautiful. You can also easily do 95% of them in a stock gladiator too, as long as you're with a group not by yourself. Look up the Georgia Jeep Alliance group on FB and tag along for a ride or too. You'll learn more in an hour of real world experience with them than you will days of research on the internet.

You sound like you drive like me, 65-70 at the highest. I run a small 37" (BFG tires run small compared to others) and I'm perfectly happy with 5.13's.

Without wheeling you could fit 35's without a lift, you'd rub offroad as you flex the suspension. Stepping up to 37's is a jump requires a lift, ect... To start I'd wheel the Jeep exactly as it is now. Maybe find a set of Rubicon takeoffs off FB Marketplace or somewhere and run the 33's for a bit with no other changes. Feel the difference, see how you like it, ect... Once you run that for a bit, then decide if you want to step up to 35's or 37's. IMO the jeeps today are way different than what you might have owned in the past. Factory 44's front and rear already. to put 37's on a TJ was an overbuilt rig, 37's on a Gladiator are almost commonplace. 40's are the new 37's.

On the flip side, if you don't mind revving the Jeep up a bit and recognizing Jeeps are better low speed vs 80mph interstate vehicles, I've heard several people run 5.13's and 35's and it's not a terrible combination. Definitely more fun around town, but you wouldn't want to do that if the Jeep is 90% interstate driven.

 

[JPJ987]

I live in GA too, east of Atlanta. Do you intend to wheel any? I know you say you haven't seen a mountain or rock recently, but driving through the N. GA mountains is one of the biggest benefits of owning a capable Jeep. Not about abusing or bashing to Jeep, but the forest and service roads running all through N. GA are beautiful. You can also easily do 95% of them in a stock gladiator too, as long as you're with a group not by yourself. Look up the Georgia Jeep Alliance group on FB and tag along for a ride or too. You'll learn more in an hour of real world experience with them than you will days of research on the internet.

You sound like you drive like me, 65-70 at the highest. I run a small 37" (BFG tires run small compared to others) and I'm perfectly happy with 5.13's.

Without wheeling you could fit 35's without a lift, you'd rub offroad as you flex the suspension. Stepping up to 37's is a jump requires a lift, ect... To start I'd wheel the Jeep exactly as it is now. Maybe find a set of Rubicon takeoffs off FB Marketplace or somewhere and run the 33's for a bit with no other changes. Feel the difference, see how you like it, ect... Once you run that for a bit, then decide if you want to step up to 35's or 37's. IMO the jeeps today are way different than what you might have owned in the past. Factory 44's front and rear already. to put 37's on a TJ was an overbuilt rig, 37's on a Gladiator are almost commonplace. 40's are the new 37's.

On the flip side, if you don't mind revving the Jeep up a bit and recognizing Jeeps are better low speed vs 80mph interstate vehicles, I've heard several people run 5.13's and 35's and it's not a terrible combination. Definitely more fun around town, but you wouldn't want to do that if the Jeep is 90% interstate driven.

Yeah man, I'm originally from upstate NY, plenty of mountains and snow there. In 2018 we were originally trying to buy a place in Chattanooga TN and 35 acres on the Cumberland Plateau, but then we fell in love with North Georgia and put offers on places in Cohutta, Ringgold, and Summerville, but then market was so hot every time we got down here to look at something they were sold, so it didn't work out. So we went south more into Georgia. Very happy here, love Georgia. Thanks for the offer but I don't see us off roading anymore, just not in the tea leaves. North Georgia and the Smokey Mountains have been some of the prettiest places we've seen though.
I just want to have it in a garage, jack it up, pull the top and doors off and go whenever I want, and with the weather down here it will be often.
This is all positive, I wasn't sure of the limitations with the Gladiator, but now it sounds like it can happen. On a stock Gladiator Sport you can fit 35s? So you have 37s and 5.13s, what's the width of those 37s and what lift kit are you using? And what Jeep do you have? Motor? and are you running offset rims or wheel spacers? Right now is the time when I have to do it, in the coming year or so I will step back from my business and retire for the most part and I don't know if I'll be in a position to invest the money in a couple of years and I'd hate to regret not doing it. But since I won't be off road, you think I could squeeze 35 x 12.5s on there? I thought on a Rubicon it would be fine, but on a Sport? I would definitely forego the 37s if I could do that. I would imagine if I just pushed the wheels out clearance would be fine. Either way I'll switch the gears but saving the money on a lift kit would be nice and I like the lower stance anyway. I was told that a 2.5 spacer kit could be used, but like the it was mentioned at the beginning of this thread, the ride is not as nice. I also saw some tire reviews that had a guy with a Gladiator sport using 33/13.5R15s and he loved them. I would probably keep it 17s, but I could see that being a good look too. I know the 33 will work, I'm assuming I would just need the proper offset to accommodate the width. Am I right? On my Ram I've had Maxi Razr MT 285/70R17s on for over two years on these super hot Georgia roads, carrying weight and towing constantly and those tires have been fantastic, still going. So the Maxxis Razr MT 295/70R17s (33.5" high, 12.3 wide) or the MT 305/70R17s (34" high, 12.8 wide) might be a better option, I could save on then lift but put the money into the gears. As long as I offset and keep the same distance between the back of the tire and the wheel well I shouldn't have any rubbing issues, correct? And like you said earlier, you think I can run 33s and use the 3.73s? Do you think I would lose a lot of power jumping from 31s to 33s? I do like the look of that 33/13.5s. I wouldn't mind dropping to a 15" rim either, do you think there's any issues with that? I appreciate your time and knowledge very much, thank you!

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