I Finally Did It (37s on the way)

[TheHops]

(Heads up--longer post, with some background, justification and number crunching.)

TL;DR, I'm switching from 35s to 37s and expect to see performance improvements across the board.

I will be making the change from Nitto Ridge Grappler, 35x12.5R17 E-load tires, to BFG KO2, 37x12.5R17 C-load tires.

I recall saying early on in my build that I had zero interest in going over 35" tires. Well, fast-forward a little over three years and here we are. So, what changed my mind?

• I installed a Clayton 2.5" lift that ended up giving me over 3 inches front and rear. If I had gotten 1.5" to 2.5" of lift, as I had expected to considering the amount of weight I have added to my rig, I would have stuck with 35s. There is more than enough space for 37s in the wheel wells on my Rubicon. I have been running this lift for about 9 months now.
• I relocated from the south (TN), to up north (upstate NY), and wanted/needed to purchase snow-rated tires. Since I was going to make a purchase anyway, now was the time to do it.
• I came across a deal that I couldn't pass up.
• Science (more on this below).

I have always preached function over form in terms of my build, and that fact isn't changing. I have never come across conditions where my 35s did not get me through. Having said that, I now have the space for 37s. Initial thoughts are that I'll see reduced fuel economy...but I'm not so sure (reference the data below). Also, the extra ground clearance and the snow rated tires will be huge once the snow starts to fall in terms of several feet instead of inches up here off of the Lakes. I did a brief review on my youtube channel (https://www.youtube.com/@TerraOutdoors) of Ridge Grapplers in some mild winter weather in TN and they did perform admirably. Having said that, that was snowfall in inches with some light ice. Snowfall up here will be an entirely different animal.

I loved the Ridge Grapplers, and have had poor experiences with KO2s in the past, so we'll see how this goes. I had a sidewall separation on the highway with the last KO2s that I ran several years back. I'm hoping and praying that I don't experience anything like that with these tires. The price on these was right, so this is BFG's last chance to win me over.

So, the science behind the change. I actually crunched some numbers, and my findings were that the induced stress on the drivetrain will be *less* with this tire change. By running the numbers to find the resulting lever torque at each wheel, here's what I found. Size/weight specs were taken directly from manufacturers.

Force applied in order to roll must overcome static friction. Static friction is calculated by the force an object exerts (normal force) multiplied by how "sticky" the surface is (coefficient of static friction). I used a .8 constant for the "stickiness." With that in mind:

Nitto Ridge Grappler, 35x12.5R17, E-load
268.48 N static friction * .441452 m (or, 34.76 inch overall diameter divided by two--which is 17.38 inches from fulcrum to outside of tire) = lever torque of roughly 118.5 Nm to start rolling

BFG KO2, 37x12.5R17, C-load
230.56 N static friction * .46355 m (or, 36.5 inch overall diameter divided by two--which is 18.25 inches from fulcrum to outside of tire) = lever torque of roughly 101.8 Nm to start rolling

That means induced stress will be reduced by 16.7 Nm per wheel. That is significant, especially considering the fact that I will be going *up* in tire size. With a manual transmission, I may still need to regear down the road (I rarely come out of 4th gear on the highway as-is), but the reduced stress, and the reduced weight/rolling mass of each wheel, almost makes me wonder if I may see an *increase* in fuel economy. Time will tell. Regardless, the expected increase in performance due to clearance/snow rating, the expected improvement in road manners going from E to C load, and the reduced stress at the wheels/on the axles was enough for me to buy-in and make the change.

I'll be sure to drop updates on my build page (https://www.jeepgladiatorforum.com/forum/threads/ares-build-thread.26187/) for anyone that is interested.

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[gladtohave]

(Heads up--longer post, with some background, justification and number crunching.)

TL;DR, I'm switching from 35s to 37s and expect to see performance improvements across the board.

I will be making the change from Nitto Ridge Grappler, 35x12.5R17 E-load tires, to BFG KO2, 37x12.5R17 C-load tires.

I recall saying early on in my build that I had zero interest in going over 35" tires. Well, fast-forward a little over three years and here we are. So, what changed my mind?

• I installed a Clayton 2.5" lift that ended up giving me over 3 inches front and rear. If I had gotten 1.5" to 2.5" of lift, as I had expected to considering the amount of weight I have added to my rig, I would have stuck with 35s. There is more than enough space for 37s in the wheel wells on my Rubicon. I have been running this lift for about 9 months now.
• I relocated from the south (TN), to up north (upstate NY), and wanted/needed to purchase snow-rated tires. Since I was going to make a purchase anyway, now was the time to do it.
• I came across a deal that I couldn't pass up.
• Science (more on this below).

I have always preached function over form in terms of my build, and that fact isn't changing. I have never come across conditions where my 35s did not get me through. Having said that, I now have the space for 37s. Initial thoughts are that I'll see reduced fuel economy...but I'm not so sure (reference the data below). Also, the extra ground clearance and the snow rated tires will be huge once the snow starts to fall in terms of several feet instead of inches up here off of the Lakes. I did a brief review on my youtube channel (https://www.youtube.com/@TerraOutdoors) of Ridge Grapplers in some mild winter weather in TN and they did perform admirably. Having said that, that was snowfall in inches with some light ice. Snowfall up here will be an entirely different animal.

I loved the Ridge Grapplers, and have had poor experiences with KO2s in the past, so we'll see how this goes. I had a sidewall separation on the highway with the last KO2s that I ran several years back. I'm hoping and praying that I don't experience anything like that with these tires. The price on these was right, so this is BFG's last chance to win me over.

So, the science behind the change. I actually crunched some numbers, and my findings were that the induced stress on the drivetrain will be *less* with this tire change. By running the numbers to find the resulting lever torque at each wheel, here's what I found. Size/weight specs were taken directly from manufacturers.

Nitto Ridge Grappler, 35x12.5R17, E-load
335.6 N (or, 75.45 lb tire weight) * .441452 m (or, 34.76 inch overall diameter divided by two--which is 17.38 inches from fulcrum to outside of tire) = lever torque of roughly 149.2 Nm

BFG KO2, 37x12.5R17, C-load
288.2 N (or, 64.8 lb tire weight) * .46355 m (or, 36.5 inch overall diameter divided by two--which is 18.25 inches from fulcrum to outside of tire) = lever torque of roughly 133.6 Nm

That means induced stress will be reduced by 15.6 Nm per wheel. That is significant, especially considering the fact that I will be going *up* in tire size. With a manual transmission, I may still need to regear down the road (I rarely come out of 4th gear on the highway as-is), but the reduced stress, and the reduced weight/rolling mass of each wheel, almost makes me wonder if I may see an *increase* in fuel economy. Time will tell. Regardless, the expected increase in performance due to clearance/snow rating, the expected improvement in road manners going from E to C load, and the reduced stress at the wheels/on the axles was enough for me to buy-in and make the change.

I'll be sure to drop updates on my build page (https://www.jeepgladiatorforum.com/forum/threads/ares-build-thread.26187/) for anyone that is interested.

 

[TheHops]

I'm trust trying to help out.

Everyone, go tell your spouses/significant others that you have to get larger tires, because science said so!

 

[kevman65]

Not to burst your bubble, but your snow rated tires won't matter when you're parked at home because you just got 3 feet of lake effect snow

 

[TheHops]

Not to burst your bubble, but your snow rated tires won't matter when you're parked at home because you just got 3 feet of lake effect snow

Haha, fair point. From what I've been told, the roads are well-maintained up here--until the snowfall outpaces the plows. At that point, it's every man for themselves.

My job doesn't shut down due to weather. Regardless of how bad it gets, there's always a chance of being called in. If I do have to at least make an effort to get out, I'd rather have something with a wider safety margin.

 

[Bjeepz]

It's not that bad lol, I live just North of there in Canada and winter is winter. Another perk of lake effect is less snow overall in my experience living on Lk Erie in the past. Only downside to your choice is the BFG's aren't exactly great snow tires... For a lighter 37 the Cooper AT3 XLT would offer much better snow and wet weather performance, because siping!

 

[TheHops]

It's not that bad lol, I live just North of there in Canada and winter is winter. Another perk of lake effect is less snow overall in my experience living on Lk Erie in the past. Only downside to your choice is the BFG's aren't exactly great snow tires... For a lighter 37 the Cooper AT3 XLT would offer much better snow and wet weather performance, because siping!

It'll be a lot worse than TN snow, that's for sure. ?

I've had good experience with Coopers in the past. I would have gone with those, or Falkens, if the price was even remotely close to what I paid for the BFGs.

Speaking from experience, I know the KO2s will be much better in snow than the Ridge Grapplers, so that's a plus.

 

[Bjeepz]

It'll be a lot worse than TN snow, that's for sure. ?

I've had good experience with Coopers in the past. I would have gone with those, or Falkens, if the price was even remotely close to what I paid for the BFGs.

Speaking from experience, I know the KO2s will be much better in snow than the Ridge Grapplers, so that's a plus.

Ha ya the fun humid wet slick snow we get in the North East!

Same here for Coopers and I'm on my 4th set of Falken AT3W's now. No brand loyalty, it has just worked out sizing and pricing when needing tires on the different vehicles (Tacoma, JL, JT, 4Runner, ZR2, Mojave!) I would make the same choice as you on the BFG if the price was significantly better. In Canada I am seeing the 37x12.5r17's at over $600 per tire right now, craziness.

Hope they work out great for you!

 

[bucolic]

Not to burst your bubble, but your snow rated tires won't matter when you're parked at home because you just got 3 feet of lake effect snow

You'll be stuck in way less than 36" of snow. Once it gets to about 18 to 20", regular 4wd pickup trucks start to have problems with the snow building up under the truck and basically lifting it off the ground and getting stuck. Not sure how much more a lifted Jeep would help. Maybe a couple more inches. But I suspect 20" of unplowed snow, and you'll start to have issues. Tires won't make a bit of difference if they ain't touching the ground! Would love to see this in action though! I could be completely wrong, and you'll plow through like nothing.

 

[TheHops]

You'll be stuck in way less than 36" of snow. Once it gets to about 18 to 20", regular 4wd pickup trucks start to have problems with the snow building up under the truck and basically lifting it off the ground and getting stuck. Not sure how much more a lifted Jeep would help. Maybe a couple more inches. But I suspect 20" of unplowed snow, and you'll start to have issues. Tires won't make a bit of difference if they ain't touching the ground! Would love to see this in action though! I could be completely wrong, and you'll plow through like nothing.

I feel like I've seen numerous snow wheeling videos of people plowing through more than that. I personally haven't been in those types of conditions in many years though, and definitely not in thr Gladiator, so who knows! I'm looking forward to playing in it though either way!

 

[JTGuy]

One of my fears of going 37 is even with 4.88s there will be a loss of snappy performance. For those that have done it I want to know it's going to be great.

 

[TheHops]

One of my fears of going 37 is even with 4.88s there will be a loss of snappy performance. For those that have done it I want to know it's going to be great.

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 mph, I'm good, because that's about the fastest I ever go.

 

[Phishs]

Post pics when you get them installed.

 

[WanderingJ]

get ready for the salt. Im "upstate" but really, Albany. Roads are usually good unless its heavy heavy snow fall and they use a ton of salt. you'll be white in no time.

 

[TheHops]

get ready for the salt. Im "upstate" but really, Albany. Roads are usually good unless its heavy heavy snow fall and they use a ton of salt. you'll be white in no time.

Definitely not looking forward to that.

I've been pricing out undercoating. Do you recommend it? Or should I just be spraying down the undercarriage religiously? I don't plan on bring up here for the long term, so if I can manage the inevitable rust for a year or two before I head back down south, I'll be happy.

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