40" tires... Talk me out of it

[KurtP]

Where are you carrying your spare 37-40"? I spoke with a Jeep Gladiator outfitter in Victoria B.C. and he shared a story of a 37" needing to removed from the spare tire carrier with a pry bar. This is not a position that I would like to be in out in the bush by myself! I think that I will stick with a 35" tire as the preferred size and still be able to store my full-size spare under the truck.

A 37 can fit if its on the smaller side. The Clayton track bar is clearanced for full 37. It drops down a touch that may affect some instances of departure angle on large obstacles.

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[TheSharksDen]

I had 315 70 17 BFG KO2S and regretted putting them on after the first week. I've been wanting 37's ever since but the dang BFGs just last forever. I recently swapped them out for a use 70% treaded set of Goodyear Kevlar MTRs 37 12.5 17 tires I got for $550 total mounted and Balanced. I considered a 39 12.5 17 Kanati Mud Hog but the weight of the tire and having to do a regear made me decide on the 37's. I'm pleased with the look. One of the main reasons I'll never go 40's is the cost associated with getting it done and the altering of the axles plus I really like my stock steely wheels and have no desire to swap them for anything aftermarket. Sure 40's look great but I'm happy with my 37's and that will be the standard for me. I'm getting over 17mpgs which is a night and day difference from my JKU that got 12-13 at best on 37's. If I regear down the road I can make that number go up but if I don't then I'm content where I'm at and I feel like I can tackle a decent trail in my rig if I choose to and still feel comfortable driving on the road with it as well. That's important to me because it's my daily driver that I have put almost 22,000 miles on in a year of ownership. Whichever way you go I'm sure it will look great.

I went from this

To this

To this

To finally this

Buy once cry once was some advice I got a long time ago that I always fail to follow for some reason!!!!

How the hell are you getting 17mpg? I’m running 35” Ridge Grapplers and only getting 14.5 highway and 13s in city. ??

 

[Dtrues878]

I guess my point is as much to anyone reading as it is to you.

If you want to run 40’s because you want to run 40’s; then run 40’s. It’s America. Enjoy the heck out of it.

If you want a big ass Jeep because you like big ass jeeps, then build you a big ass Jeep and enjoy the heck out of it.

If you want to bash down the hardest of hard core trails, and have a shit ton of cash to burn (I dont) then build you a big ass truck on Dana 60’s and 40-42’s and enjoy the heck out of it.

But if the question is “hey, i want to wheel this thing, what do I need?” Then you probably dont need 40’s. And you DEFINITELY need to be aware of what is truly involved in going to a tire that big to actually wheel it.

I fully admit I have 37’s because of the look. I knew what parts I wanted for my lift for the drive I know I wanted. When that was done, with the spring rates i wanted, with the shock mounts that worked with my Mojave shocks, a 35 would have looked too small. Had there been a 35” option at the time, i would have probably gone that route. But I know what comes with going 37’s, and the trade offs were worth it. It meant lift. And gears. And ball joints. And a tie rod. And a drag link. And the control arms. It will mean chromo shafts sooner rather than later. Etc I can park at work and in my garage, so,

Its a personal thing, that i think a lot of people see ‘gram builds flexed out (and it does look cool) and think thats what they “need” to go wheeling/camping. This steers people wrong and into builds that are too involved, too expensive, and too extreme for what they want. Now you cant park in the garage deck. Or in the garage at home. Its a pain in the ass to drive around. It costs to maintain it. Etc etc etc I mean shit. You toss on the absolute bare minimum to run 40’s, and you could end up with death wobble your first drive to work or on a trip with your kids on the interstate and flip the jeep. You might break your axle shaft your first wheeling trip; and if youre by yourself or with another guy who doesnt know shit about fixing trucks and you’re PROPER fucked.

Id just hate for someone to come here asking for advice; possibly be on a budget; and get steered into something too deep and end up hating life because of the burden.

Oh yeah I totally get it and I was just joking around and really do appreciate all off the help! The last thing I want is to well get in the exact situation you laid out here do to my own inexperience.

I think it's safe to say I have been steered away from the 40's and won't regret 37's! I am excited to build up this truck and learn as much as possible during this journey and try not to make many mistakes with the help of all of you guys!

thanks so much!

 

[Dtrues878]

I have very little experience Jeeping, I purchased a Gladiator 2 months ago and than my brother and dad purchased one also. We all did the Mopar lift with a additional level and a pass through steering shock. I did 37's and so did my brother but told my dad to go with the 35's. No doubt the Jeep is happier with the 35's but I am very happy with the 37's. I can drive around the the 4:10 gears but absolutely needs to be re geared. I have no intention to do any advanced rock crawling but more over landing with mild to medium obstacles. For example the Devils Race Track in the swell etc. With all that said I personally would not do 40's but if that is what you want than do it.

I do have a couple mild regrets with the Mopar lift and am going to upgrade to teraflex control arms that are adjustable for more castor for better highway manners. Also it needs about another inch in the front to sit level and planning on getting some adapters to kick the tires out another inch ( if this is a bad idea please let me know).

I am also doing a bunch of paint work this coming week and absolutely love this vehicle.

Mine

Dad's with 35's

Nice looking trucks! I agree with you on not getting the 40's. What paint work are you getting done?

 

[Sublime]

Great Thread. Been planning my build as well and this has been a big internal debate as well. I am still looking to go with 40s though. But one thing I have settled on is reducing the size rim I originally wanted. First plan was 24x14s wrapped with 40s. Now I'm going to reduce to 22x12s still on 40x15.5s though. I figure I start here and if I see the potential issues starting sooner than later I can always downgrade to 38s or 37s. Probably 38s since that isnt as common. If I went with a 24x14 wheel I wouldnt be able to reduce the size tire without a nasty stretch. Plan to do 5.13 gears as soon as wheels Installed potentially before I even drive it off the lot.

I can build up axles and other support little by little. I wont be wheeling. Couldnt handle the scrapes, dings, dents and risk of a major failure. It will be a daily driver on highway and overall I want it to look my way.

 

[Eazye]

I went with a Clayton 2.5” lift and 3/4” leveling puck in the front, but I’m also in a Rubi which has the higher fenders. I’d think the 3” RK kit with 37” tires would be a good setup for Daily driving. I’m running Patagonia MTs which when aired up properly are super quiet for an mt at well so no screaming to talk in the Jeep! The maroon Gladiator is a buddy’s stock Willys compared to the 2.5” and 37s on my Rubi.

 

[Dtrues878]

I went with a Clayton 2.5” lift and 3/4” leveling puck in the front, but I’m also in a Rubi which has the higher fenders. I’d think the 3” RK kit with 37” tires would be a good setup for Daily driving. I’m running Patagonia MTs which when aired up properly are super quiet for an mt at well so no screaming to talk in the Jeep! The maroon Gladiator is a buddy’s stock Willys compared to the 2.5” and 37s on my Rubi.

That looks great! I cannot wait to see mine transform. Did you get a new grill or wrap yours? That is another thing I plan to do. I found a grill on marketplace for $60 that I was going to practice wrapping and if it looked good replace mine.

 

[Jeeperjamie]

How the hell are you getting 17mpg? I’m running 35” Ridge Grapplers and only getting 14.5 highway and 13s in city. ??

Not sure but I was getting close to 19 on 315 70 17 BFG KO2s. I'm at 17.4 as I type right now and it sits in the driveway. I got a Max Tow with 4.10 gears. I also rarely drive over 75 on the interstate. The speedo is dead on based on google, sheriff's radar, and about 3 gps apps.

 

[JD D05]

Nice looking trucks! I agree with you on not getting the 40's. What paint work are you getting done?

I am going to sand down and have the back section of the hard top painted white. Idea is the black roof line will flow with the rock sliders. Also having the door handles painted white to match. Having the black plastic piece behind the grill painted a Grey color to match the wheels and the side vents gray. Having the 1941 sticker removed and all the badges and stickers. I have a new bumper for it that will be powder coated to match the wheels.

 

[Summitsearcher]

I went with a Clayton 2.5” lift and 3/4” leveling puck in the front, but I’m also in a Rubi which has the higher fenders. I’d think the 3” RK kit with 37” tires would be a good setup for Daily driving. I’m running Patagonia MTs which when aired up properly are super quiet for an mt at well so no screaming to talk in the Jeep! The maroon Gladiator is a buddy’s stock Willys compared to the 2.5” and 37s on my Rubi.

Dude! That Rubi is bad ass!

 

[FLUndertaker]

I guess my point is as much to anyone reading as it is to you.

If you want to run 40’s because you want to run 40’s; then run 40’s. It’s America. Enjoy the heck out of it.

If you want a big ass Jeep because you like big ass jeeps, then build you a big ass Jeep and enjoy the heck out of it.

If you want to bash down the hardest of hard core trails, and have a shit ton of cash to burn (I dont) then build you a big ass truck on Dana 60’s and 40-42’s and enjoy the heck out of it.

But if the question is “hey, i want to wheel this thing, what do I need?” Then you probably dont need 40’s. And you DEFINITELY need to be aware of what is truly involved in going to a tire that big to actually wheel it.

I fully admit I have 37’s because of the look. I knew what parts I wanted for my lift for the drive I know I wanted. When that was done, with the spring rates i wanted, with the shock mounts that worked with my Mojave shocks, a 35 would have looked too small. Had there been a 35” option at the time, i would have probably gone that route. But I know what comes with going 37’s, and the trade offs were worth it. It meant lift. And gears. And ball joints. And a tie rod. And a drag link. And the control arms. It will mean chromo shafts sooner rather than later. Etc I can park at work and in my garage, so,

Its a personal thing, that i think a lot of people see ‘gram builds flexed out (and it does look cool) and think thats what they “need” to go wheeling/camping. This steers people wrong and into builds that are too involved, too expensive, and too extreme for what they want. Now you cant park in the garage deck. Or in the garage at home. Its a pain in the ass to drive around. It costs to maintain it. Etc etc etc I mean shit. You toss on the absolute bare minimum to run 40’s, and you could end up with death wobble your first drive to work or on a trip with your kids on the interstate and flip the jeep. You might break your axle shaft your first wheeling trip; and if youre by yourself or with another guy who doesnt know shit about fixing trucks and you’re PROPER fucked.

Id just hate for someone to come here asking for advice; possibly be on a budget; and get steered into something too deep and end up hating life because of the burden.

Preach it brother. My second Jeep was a CJ7 that I built following getting a smoking deal on a set of 42” TSLs. Of all the stupid reasons to build a Jeep, a great deal on a set of tires it about the dumbest. I went SOA with full width axles to clear the tires. Needed Dana 60 up front and Dana 70 in the rear. A NP435 trans and a build 360 to spin it all. When I was done I had a Jeep i couldn’t drive on the street, sunk a stupid amount of money into and basically ruined a previously clean unmolested CJ. I sold it for half of what I dumped into it and didn’t own another Jeep for over a decade. I am happy with my JT on 37s. I’m reagearing and adding some bolt ons to improve capability and appearance but keeping it very streetable.
My advice is to not get sucked into a bigger and bigger dick measuring contest. There’s always a guy with one bigger and badder. Ymmv.

 

[mike921921]

As long as you throw in re-axeling, re-gearing, and supercharging, sure - go 40"

 

[Jonny A]

I bought my JTR used with 10,000 miles. It had supposedly around $5,000 in dealer installed upgrades. I paid $10,000 less than when new and prior to its upgrades. Got a great deal on my Colorado as a trade in. So for a like new, especially to me Gladiator I could not be more thrilled.

I bought it with 35" tires, line X'd steel bumpers and rock rails. I thought about 37" or even 40" tires. But like another guy said, it's starting to be like a dick measuring contest. I would keep wanting bigger I guess. Really right now with 35s, I am usually the baddest looking vehicle in the mall parking lot. LOL.

I will go off road. I will not do anything major. So anything bigger than what I have is not necessary. Probably overkill as is.

So I guess if you want to be talked out of 40's... unless you have a lot of expendable income I personally wouldn't. If I were rich and it were not a DD, then hell yeah! Go for it! But if that were the case, I would go what ever the max tire size I could get away with and be road worthy. I would want to be King Dick!

As stated earlier, I got mine on 35's and will probably always be that way.

 

[shrinkhead]

35x12.5 look pretty bad ass on 17 inch rims on a 2 inch lift. More lift needs bigger tires. A big advantage of those small tires is they accelerate much better making for more fun around town. on the trail they have advantages too re center of gravity. If you wheel that hard that you can't clear obstacles with some rubbing on 35s the JT might not be the right vehicle for that . That being said I love the look of 40s and one day I'll go there.

 

[Mopar King]

I have run 37's and 40's on my JTR. 37's were great on my 2" Mopar lift and Dana 44's, no modification needed (at this point I could only get 14-15 MPG avg). I recently did a few upgrades and decided to go to 40's. To successfully upgrade and feel I had full reliability off-road I updated: lift (now 4" long arm), UD60 axle swap with 4.88 gears, driveshafts, ram ported steering box with hydro assist and yeti steering components. I also replaced all inners and fenders, only front inners were necessary for 40's at full flex without rubbing.

If you just want your truck to "look cool" but not be truly "capable" - I have seen several guys run 40's on their Dana 44s. Most of them will run a truss kit for extra support but a few have not.

I also know of a guy who was running 40's on stock Dana 44's (no truss kit) who found some wet pavement, tried to do a burnout and snapped his axle.

Personally, I wouldn't go to 40's without the proper frame work. If its just a mall crawler - 37's look pretty bad ass too.

1st picture - 37s on 2" Mopar lift
2-5 - All upgrades done for 40's

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