33" tire weight with 3.73 gears JT sport

[clipper]

New JT sport owner here and like most, I am interested in adding a more stout looking set of wheels and tires.

A local shop is saying that 3.73 gears are totally fine with 33, 35, and even 37" tires without a re-gear.

But that doesn't seem to be the case with everything I am reading online.

I'm not going on any crazy trails, it's more of a commuter and ideally I'd like to maintain a decent mileage with this upgrade.

Can anyone shed some light on wheel / tire packages for a stock 3.73 sport and light weight A/T tires?

Is it reasonable to do this upgrade without re-gearing or will it potentially cause issues down the road?

I know that this has been brought up a handful of times but any pictures and insights of your setup will be appreciated!

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[whiteglad]

Falken Wildpeak AT3W in 255-80-17 are about 52 lb, which is 10 lb lighter than the Rubi/Moj size (285-70-17). On the flats at sea level you can get away with more tire uppsizing with 3.73 than you can elsewhere.

 

[KQL]

I just went through this dilemma myself. It required a hard look in the mirror and some painful truth pills to swallow.
1. you can’t have your cake and eat it too. Heavier tires will absolutely affect MPG and driveability. No one can tell you whether you NOW think your truck is peppy or a dog. It’ll get worse with heavier tires. But if you’re currently pleased with your power performance, it might be that you won’t be too disappointed with the decrease (these might be the people telling you “it’ll be fine”). You might then feel like you took a hit with heavier tires, but it’s still usable. People who feel their stock truck is underpowered will probably hate losing any more pep to the heavier tires.
2. how badly do you need the e-rated heavier tires? I ended up weighing tire weight most significantly in my decision and went with SL-rated 255/75r17 cooper disco 3s. Better looking than my Bridgestone at3 for minimal weight increase. They’re not 33s though.

 

[steveorama]

I have 3.73 gears on my Overland and I run 275/70R18 (33s) Cooper Discoverer ATPs and have no noticeable issues after I recalibrated the tire size in the system. They are fairly light tire (58lbs) though. I've ran trails and plenty of city and highway miles and I'm happy with this setup, but I understand I'm probably leaving some power on the table by not running 4.10s. You can of course run larger tires on the 3.73s, I wouldn't go above a 35 personally with that factory gearing without it feeling lethargic. To maintain your ratios I believe you would need to go to 4.88s to run 35s and 5.13s to run 37s FWIW.

Regearing is expensive and no one ever knows you did it but you, so it's not a popular mod. So I'm not surprised to hear a shop say you can run larger tires with stock tires. They probably do thousands of the them, but that doesn't mean it's the right way to do it either. They are in the business of selling tires after all.,

 

[JTBurns]

You should take lift costs into consideration as well. You'd certainly need one for 37's and most likely would need one for 35's as well. You'll have no problem running 33's, and rubi and Mojave takeoffs 285/70/17 are usually available in the member marketplace, craigslist, or FB marketplace near you. I've run the Falken MT takeoffs for over 30k miles without issue. I'm going to go with a 34-35" tire (295/70/17, 285/75/17, or 255/85/17) that fits the stock wheels next, and will at least need to level the truck to accommodate it. Those sizes seem to be the limit of the 3.73s, especially if you add a bunch of weight to the truck or plan to tow at all.

 

[clipper]

I plan on going with a level kit and would love to add 35's if possible. I am in FL and it won't see much of the hills until we eventually take it on a trip.

My biggest concern is burning out the transmission with the 35's and responses I find online are usually subjective to geographic location.

Are you guys finding all 8 gears when switching to 35's with 3.73 ratio?

 

[OVERLORD]

Running 33's on an Overland, gas mileage minimally affected. 285-65-18.

 

[Gren71]

I went with 255/75/17 Dueler ATs that someone took off their bronco. They’re only a couple pounds heavier than the stock sport 245/75s and just slightly wider.

Both tire weight and tread width will eat your mpg if thats a concern, it was for me.

You can use this to compare what you’re looking at vs your stock size.

https://tiresize.com/comparison/

 

[Jeeperjamie]

A 33 you will be fine. When you get into the 35 and 37 inch range that's when you got to start looking at the weight on them. A lighter 35 like a BFG, Cooper, Kanati's to name a few will be fine and be under 70lbs. It's still going to affect MPGs though. Your definitely gonna have to think about a regear if you move to 37's with 3:73 gears, just not going to cut it. You want find a 37's under 70lbs. BFG, Kanati and Goodyear make some of the lightest ones and those are 72lbs. Most are mid 80lbs weight wise.

Like someone said, your jeep may feel different to you than someone else so a shop can't say this or that and be accurate. I've had a shop tell me that 35's wouldn't affect gas mileage which I knew was wrong. I got 4:10 gears on mine and run Kanati trail hogs in a 37 12.5 17 and mine still feels Peepy enough to drive and tow. I average right around 17 to the gallon and have no problems merging into traffic or passing. My tires are 72lbs a piece. If you put that tire on yours it's gonna get probably around 15 mpg's depending on how you drive. I baby mine most of the time and keep it under 75 for the most part and stay with in 4 or 5 miles of the speed limit in most places.

 

[clipper]

A 33 you will be fine. When you get into the 35 and 37 inch range that's when you got to start looking at the weight on them. A lighter 35 like a BFG, Cooper, Kanati's to name a few will be fine and be under 70lbs. It's still going to affect MPGs though. Your definitely gonna have to think about a regear if you move to 37's with 3:73 gears, just not going to cut it. You want find a 37's under 70lbs. BFG, Kanati and Goodyear make some of the lightest ones and those are 72lbs. Most are mid 80lbs weight wise.

Like someone said, your jeep may feel different to you than someone else so a shop can't say this or that and be accurate. I've had a shop tell me that 35's wouldn't affect gas mileage which I knew was wrong. I got 4:10 gears on mine and run Kanati trail hogs in a 37 12.5 17 and mine still feels Peepy enough to drive and tow. I average right around 17 to the gallon and have no problems merging into traffic or passing. My tires are 72lbs a piece. If you put that tire on yours it's gonna get probably around 15 mpg's depending on how you drive. I baby mine most of the time and keep it under 75 for the most part and stay with in 4 or 5 miles of the speed limit in most places.

37s are a little much for my use but look awesome.

Did you find all gears when you had 35s before re-gearing?

 

[BlueScapegoat]

I ran some BFG T/A KOs in a 33x10.5r15 flavor on my TJ way back in the day. They were super light, and still my favorite mostly-street-driven all terrain to this day.

It looks like BFG makes a 34x10.5r17 T/A KO2 now. 54.7 lbs list. Being a narrow tire will make it look taller too, imo. That'd be a cool size.

 

[Orange01z28]

I had some heavy 35" muds (Toyo Open Country MTs) with the stock 3.73s for almost 2 years. I lost probably 4 mpg over stock on average, but if you don't have a heavy foot you can still squeeze out a 20 mpg from time to time

This summer, I put on 37" Patagonia XTs which are a true 37" but the same weight as the Toyos. On the road, I could really feel no discernable difference than the 35s. I only really felt a struggle off road; I had to do 4Lo and 1st gear for a relatively simple climb

If you're really only driving on-road in Florida (no hills) i'm going to agree with your tire shop and say you'll be fine even with 37s on stock gears. You'll never see 8th gear on the freeway again, but the 8 speed will really balance everything else out

 

[Jeeperjamie]

37s are a little much for my use but look awesome.

Did you find all gears when you had 35s before re-gearing?

I've had 4:10 gears and still have 4:10 gears. I still get into all my gears on 37's with no problem. Mines a Max Tow for reference. I will not regear unless I decide to go to bigger tires. I saw around 18.7 average mpgs on BFG KO2 35's

Here some YouTube clips of mine

35's


37's


Speedo was set dead on for both using JScan and both had pretty much the same setup other than tire size. The jeep looks like this

 

[Rocksalt]

JT Sport S with 3.73 gears automatic. Running BFG KO2 285 70 17. Black Rhino wheels which are 10lb heavier than oem wheels. Does fine. avg 20 mpg

highway

 

[MrZappo]

I have 4:10 33's. It's fine. 35 might be fine, 37 would be a dog.

3:73 ? On 37's ? Someone is smoking crack.

They just want to sell you tires. It ain't just the weight, it's the larger circumference. It makes a massive difference.

On 33's, I sometimes don't see 8th if it's windy or I hit a small hill.

Save yourself the hassle and be reasonable. 3:73 is not the gear ratio to use with large tires. Sure the truck wont melt into a puddle of molten metal. But it won't be happy either.

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