I Finally Did It (37s on the way)

[MrClortho]

Ultimately I would like to regear, but to be honest I'm such a conservative driver that the loss in performance wouldn't bother me at all. As long as I can eventually get up to 65 moh, I'm good, because that's about the fastest I ever go.

It happens to the best of us when we try to justify the stock gears are fine with 37's... I was one who tried, lol.

I am just poking fun, but consider them as almost a necessity if you plan on wheeling much, making any highway trips, or towing anything more than a lawn trailer. The difference is worth the cost if you can swing it.

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[Reddout99]

I started using a product called "Fluid Film" a couple of years ago on my 2010 JKU. It has protected well in the Nebraska winters where they are not afraid to lay down salt on the roads during the winter. I applied it on the undercarriage of my JT when I got it a few months ago as well. Holds up well even when I run it through our touchless car wash that has a good undercarriage spray down. I actually run it through there fairly often in the winter.

 

[TheHops]

It happens to the best of us when we try to justify the stock gears are fine with 37's... I was one who tried, lol.

I am just poking fun, but consider them as almost a necessity if you plan on wheeling much, making any highway trips, or towing anything more than a lawn trailer. The difference is worth the cost if you can swing it.

Haha, I'd definitely like to at some point! Unless there is a drastic difference though, I don't expect it'll change much how I drive. I rarely used 5th gear even while stock, and I happily spend 90% of my highway time in 4th gear now on 35s. I'm never in much of a rush to get anywhere.

I never wheel just to wheel, mostly only higher speed trails or whatever rough terrain gets between me and my campsite.

Towing, I do maybe once a year. I just pulled a 3,000 pound uhaul 900+ miles without issue on 35s, so hopefully some lighter 37s wouldn't crush that capability. Time will tell! If it murders my drivability, I'll probably expedite gears, but I'm hoping I can at least get through winter without issue.

I started using a product called "Fluid Film" a couple of years ago on my 2010 JKU. It has protected well in the Nebraska winters where they are not afraid to lay down salt on the roads during the winter. I applied it on the undercarriage of my JT when I got it a few months ago as well. Holds up well even when I run it through our touchless car wash that has a good undercarriage spray down. I actually run it through there fairly often in the winter.

I actually did pick some of that up, so it's good to hear a good review. I think I have 6 cans. Did you just spray it evenly across the entire undercarriage, or is there a particular way to apply it?

 

[Reddout99]

I actually did pick some of that up, so it's good to hear a good review. I think I have 6 cans. Did you just spray it evenly across the entire undercarriage, or is there a particular way to apply it?

Yes. Just spray a nice coat on everything. I sprayed it on a Friday evening and let it "soak" in for the weekend. I wiped off any excess with a rag. I actually keep that rag around to wipe down my control arms and shocks and anything I feel like needs it after washes. Don't get carried away, it's not needed.
LOL, 6 cans should last you for a l-o-n-g time. I only used maybe a 1/4-1/3 can on the JT, but the underside was pretty pristine before starting

 

[TheHops]

Yes. Just spray a nice coat on everything. I sprayed it on a Friday evening and let it "soak" in for the weekend. I wiped off any excess with a rag. I actually keep that rag around to wipe down my control arms and shocks and anything I feel like needs it after washes. Don't get carried away, it's not needed.
LOL, 6 cans should last you for a l-o-n-g time. I only used maybe a 1/4-1/3 can on the JT, but the underside was pretty pristine before starting

Oh, wow haha. Awesome! The 6 pack was on sale, so I figured I'd go for it! Maybe I'll spray down my sliders and bumpers too, then.

Thanks for the advice! I'll see if I can't knock that out this weekend.

 

[MrClortho]

Haha, I'd definitely like to at some point! Unless there is a drastic difference though, I don't expect it'll change much how I drive. I rarely used 5th gear even while stock, and I happily spend 90% of my highway time in 4th gear now on 35s. I'm never in much of a rush to get anywhere.

I never wheel just to wheel, mostly only higher speed trails or whatever rough terrain gets between me and my campsite.

Towing, I do maybe once a year. I just pulled a 3,000 pound uhaul 900+ miles without issue on 35s, so hopefully some lighter 37s wouldn't crush that capability. Time will tell! If it murders my drivability, I'll probably expedite gears, but I'm hoping I can at least get through winter without issue.

There is a drastic difference. I ran into a problem where I was trying to climb a bolder with the 37s and 3.73 gears, in 4lo, and was deep into the throttle but not moving. I ended up backing out and going around. After the 5.13s, I visited the same bolder and crawling up that same bolder took little effort. I also tow a 4k lb travel trailer often and it helped with that quite a bit. However, it sounds like it may not be worth the cost for you.

There is a big difference between 35's and 37's. I ran 35's for a while and they felt somewhat similar in the way the Jeep drove as the stock 32's. The 37's feel much different, much bigger, effected steering effort significantly, etc. You wouldn't think it would make that much difference but 35s seem to be kind of a threshold of sorts. I had the same experience on an HD RAM too.

 

[TheHops]

There is a drastic difference. I ran into a problem where I was trying to climb a bolder with the 37s and 3.73 gears, in 4lo, and was deep into the throttle but not moving. I ended up backing out and going around. After the 5.13s, I visited the same bolder and crawling up that same bolder took little effort. I also tow a 4k lb travel trailer often and it helped with that quite a bit. However, it sounds like it may not be worth the cost for you.

There is a big difference between 35's and 37's. I ran 35's for a while and they felt somewhat similar in the way the Jeep drove as the stock 32's. The 37's feel much different, much bigger, effected steering effort significantly, etc. You wouldn't think it would make that much difference but 35s seem to be kind of a threshold of sorts. I had the same experience on an HD RAM too.

Dang, thanks for the heads up!

I do have the 4.10s. I doubt that'll buy me much extra, but I guess it's something. From what I've read, 4.88s or 5.13s are the way to go depending on use.

Out of curiosity, do you know what the difference in weight was between your 35s and 37s? I don't think I've ever come across a review where someone *dropped* weight by going up in tire size. I'll be losing 11 pounds of unsprung weight at each wheel by going from 35s to 37s, so I'm really curious to see how it will feel.

 

[MrClortho]

Dang, thanks for the heads up!

I do have the 4.10s. I doubt that'll buy me much extra, but I guess it's something. From what I've read, 4.88s or 5.13s are the way to go depending on use.

Out of curiosity, do you know what the difference in weight was between your 35s and 37s? I don't think I've ever come across a review where someone *dropped* weight by going up in tire size. I'll be losing 11 pounds of unsprung weight at each wheel by going from 35s to 37s, so I'm really curious to see how it will feel.

According to quick Google searches, it looks like the tire/wheel combination from the 17" stock with 35x12.5 BFG to 17"x9" wheels and 37x12.5 is about 14 lbs

 

[TheHops]

According to quick Google searches, it looks like the tire/wheel combination from the 17" stock with 35x12.5 BFG to 17"x9" wheels and 37x12.5 is about 14 lbs

Thanks for pulling that up. So while your switch increased weight 14 pounds per wheel, mine will drop 11 pounds per wheel. A 25 pound weight reduction (difference between yours and mine) would be huge. This should be interesting! I'm looking forward to seeing how it performs.

 

[TheHops]

The data is in, and I'm blown away.

Same speed on cruise control. Same stretch of road. Very similar conditions (winds 9-12 mph, left quarter headwind). Both data points appropriately programmed to correct tire size by Tazer. Same Jeep loadout. Here's what I've got:

35s:

37s:

The two pictures are taken from video clips of a run between the same two signs on a stretch of highway going in the same direction. 35s returned a range of 14 - 16 mpg. 37s returned a range of 19 - 22 mpg. This was by no means done in a controlled environment, but it's about as good as I could get. Science is undefeated.

I will say that I'm...very surprised by this. And sure, there may be 1-2 mpg of error, but 6 mpg gain? Wow. Even if real-world ultimately translates to just 1 or 2 mpg of gain, I'd still be ecstatic about that.

At 11 pounds lighter per tire, I can feel the reduced stress on the driveline. Takeoffs and braking are smoother. The Jeep starts rolling with less effort. Shifts feel more leisurely. With the same driving habits I continuously found myself driving several mph faster than usual at identical points on my commute across a couple of days. Also, notice the roughly 200 rpm reduction while holding the same speed on 37s (I know this is a result of tire size and not weight, just pointing it out). Finally, the ride is MUCH more plush. I ran 32 psi on 35s, and have 30 psi in the 37s. My only regret is that I didn't make this change sooner.

While I likely will regear in the future when budget allows, I can confidently say that the Jeep drives better now than it did before. We'll see how it is after I run a few tanks of fuel through it. Can't wait to get it off road to test out that side of things.

 

[Discount Tire]

@TheHops that's crazy information. Better gas mileage is a plus. Did you have any pics with the 37's installed? Thanks for taking the time to post.

 

[AmosMoses]

I cant believe you left the beautiful free state of Tennessee for New York. All of your gains going up to a 37" inch tire have now been diminished ?

 

[TheHops]

@TheHops that's crazy information. Better gas mileage is a plus. Did you have any pics with the 37's installed? Thanks for taking the time to post.

I was very pleasantly surprised!

Not just yet! The weather has been downright crappy here the last couple of days. I'll try to post up a before and after tomorrow or the following day if the rain lets up.

I cant believe you left the beautiful free state of Tennessee for New York. All of your gains going up to a 37" inch tire have now been diminished ?

Haha, you're telling me. I was quite content to stay in Tennessee, but unfortunately, Uncle Sam had other plans.

 

[Discount Tire]

@TheHops by Uncle Sam you must mean you are military. Thank you for your service!

 

[5adventurers]

Here's what I find interesting about the stock vs 35 vs 37 argument and gearing. I had a '19 JL and had light Patagonias on it, I could peel wheels! No need/desire to regear. When I went to 37x13.50 Toyo MT, not so much and it wandered more. So I've had my JT for a few months and looking to upgrade to 37s on the Rubicon gears...again. The Pats were about 72 lbs, the BFG KO2s I believe is 64lbs ..... Those Toyos were 90+ lbs. So....pounds matter, period. I see so many people say "gonna regear" but nothing happens...basically as expensive as tires and wheels are, then you're actively choosing to spend another $2k for gears. No thanks! Buy light tires and you don't need gears. The caveat. Someone who actively rock crawls.... But for those daily drivers, and off-roaders...I'll stick to light tires with gears and a wonderful transmission.

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