37” Tire Regrets?

[nolimits]

I was still averaging around 18 mpg with the 2.7 and KM3 35's which weigh around 74 lbs I think. These lighter 37's might help my mpg go up! I did notice that my speedometer seems dead on now with the 37's with every speed trap I have passed so far and I have not modified anything to correct the speedo. My speedo was always reading high with the 35's stock from the factory.

Tire weight definitely matters but even if you take that out of the equation, there is still more of a strain. Easiest way to visualize is think of a 10-speed bike. You use different gears/size of sprockets to get to speed. When you change the tire size you are effectively changing things.

Often when the change is small you don’t feel it. Larger changes are more obvious. Weight + size change is even more obvious. Using ProCal to add a tune is sort of a band aid fix that resolves the power loss.

Eventually if it gets bothersome enough, a true regear is the answer.

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[JL8jeff]

Tire weight definitely matters but even if you take that out of the equation, there is still more of a strain. Easiest way to visualize is think of a 10-speed bike. You use different gears/size of sprockets to get to speed. When you change the tire size you are effectively changing things.

Often when the change is small you don’t feel it. Larger changes are more obvious. Weight + size change is even more obvious. Using ProCal to add a tune is sort of a band aid fix that resolves the power loss.

Eventually if it gets bothersome enough, a true regear is the answer.

Yes, that is one of the reasons I wanted the Sas package with the 4.7 gears and the 10 speed auto which helps minimize the affect of the tire size increase. In the slightly older vehicles with the 4 speed auto, you could definitely tell the affect the larger tires had.

 

[HoosierDaddy]

They blow the factory K02's out of the water in snow, ice, rain, mixed percitpitation.

LOL, I meant to mention that I had a 4 door Badlands for 9 months ... the factory BFG's were a damn site better than the Toyo's in all the conditions you mentioned.
LOL.

 

[Charles Miller]

Not sure I’d classify them as pizza cutters but Nitto makes a 37x11.5. Comes in at 71# and actual measurements of 36.5 x 11.4 on a 9” measured rim. You loose/gain about 0.20” for every 0.50” variance in actual rim width vs measured rim width. So adjusted for 8.5” rims these would measure out closer to 36.5 x 11.2.

https://www.tirerack.com/tires/tires.jsp?tireMake=Nitto&tireModel=Recon+Grappler+A/T&partnum=715R7REG&vehicleSearch=false&fromCompare1=yes



Weight is certainly worth paying attention to regardless of size. While this topic is around 37’s, the reality is the stock GY’s @ 52# in a 35” is hard to beat/match even if you upgrade to other 35’s. No doubt the 37’s are heavier but a lot of the variance is due to the GY’s being so crazy light weight.

Another savvy way to trim weight is wheels. RTR Evo6 in 17x9 is only 22.5# and the RTR Tech6’s are only 26#. Some Methods are in the mid to upper 20’s. Stock SAS wheels are 34# with beauty rings and will go up with true beadlocks. Other options exist but forged and lightweight is usually pricey.

On a separate note, I optioned for Eibach coilovers with HD springs and Icon tubular UCA’s with delta joints. Coupled with Icon Rebound Pro 17x8.5 +25’s with 37x12.5 Yoko Geolander MT’s. Wheels around 28# per Dusty. Tires around 76# and measure 36.8 x 13.1 on a 10” rim (12.5 adjusted to 8.5” rim). Not sure all the dial ins required yet — install is scheduled for 1/13.

FWIW, was going to run Cooper STT Pros but they seem to be on back order. The Yokos were my #2 choice.

How are 37” tires on the Eibachs? I have the Eibachs and feel that I should upgrade to 2.5 shocks for 37” tires.

 

[nolimits]

How are 37” tires on the Eibachs? I have the Eibachs and fell that I should upgrade to 2.5 shocks for 37” tires.

I’m not sure yet. Install is scheduled for 1/13 so I will be able to comment more after everything is done.

However, there is a Shocks Surplus review that heavy 37’s can be problematic. In their case, 35# over stock SAS setup so near 90# tires.

Not sure what you’re running but may be worth a read. However, at the time of that writing Eibach didn’t offer the coilovers kit with the HD springs. I would assume the stiffer springs could change dynamics some.

Given I ordered the coilover kit with front & rear HD springs and my 37’s are about 76#, as opposed to 90#, I expect better results. Also much like the review I am also going to run the Icon tubular delta joint (DJ) UCA’s. Lastly once installed and fine tuned, I have a RockJock rear relocation bracket on hand to install if needed, which I suspect it may.


https://www.shocksurplus.com/blogs/news/ride-review-eibach-2-0-coilovers-on-the-ford-bronco

 

[Oldhippie]

37s seriously overwhelmed my Sasquatch coilovers…going to 4wp/procomp coilovers solved it…

 

[Fordified1]

I wouldn’t call them regrets, but it took so much more effort than I anticipated. I started with new wheels (0 offset), and Stage 6 ICON suspension. Thought I would be okay. But I was rubbing pretty hard. So I had to (in order):

The first three were before leaving the shop that installed suspension/wheels:
- Modify the OEM running boards, cutting back about 2” on the front, then a lot more finagling to get the cap back on
- Cut off the crash bar behind the front tires
- Remove mudflaps

Then it was still rubbing in many on-road scenarios that lead to:
- JKS Max Tire Clearance kit was the big unexpected one
- 1” Body lift to prevent stuffing the front tires

Soon enough I removed the OEM steps and replaced with IAG rock rails…and even those rubbed, so back to the grinder to trim those back.

After all that, it still rubs a bit in the back at full articulation on the trails. That one I can live with for now.


On top of that, my gas mileage went from about 15.5 to 13.5. I haven’t recalibrated the speedo so maybe that would increase slightly but wouldn’t top 14.

Sure looks good and works great on the trails.

Where does it rub in the back? Would a different offset wheel cure that or cause new problems in the front? I’m looking at 2 offsets in the same wheel. +12 and 0. Not sure what to get.

 

[SROC3]

How are 37” tires on the Eibachs? I have the Eibachs and feel that I should upgrade to 2.5 shocks for 37” tires.

I'm gonna chime in just to give my 2 cents here. I have a buddy on 37s who has the Eibach Coilovers - he does a Ton of rock crawling and slow-to-regular speed trail runs. For that application, the Eibachs are perfectly fine and will serve you well. I have 35s and have KING 2.5s. I do not really like rock crawling an entire trail, if obstacle then yes. But I do 90% of my trials at higher speeds and for extended periods. So the KINGs, with the external adjustors, are perfect for it. Now - if I were to go to 37s, getting near bottoming out, or hitting it, is going to give me another set of issues I would have to deal with. Maybe do a body lift to ensure total clearance for the wheels. But on the flip side....if all I did was trails like my buddy, then there would be no issues.

What I'm getting at here is think of the your application first. How will you use your Bronco? And you will find your answer and arrive at the most suitable solution for your needs.

 

[BUCKIN6VA]

Where does it rub in the back? Would a different offset wheel cure that or cause new problems in the front? I’m looking at 2 offsets in the same wheel. +12 and 0. Not sure what to get.

I'm still not sure where in the back it's hitting but I think it's just a piece of plastic that hangs down behind the tires. Possibly rubbing the bumper itself - but this is a rare issue, only when fully, fully flexed out on a trail. 99.9% of the time I don't experience any rubbing in the back. Can't comment if offset would fix it.

 

[Flying Skunks]

How are 37” tires on the Eibachs? I have the Eibachs and feel that I should upgrade to 2.5 shocks for 37” tires.

I have had Zero issues , and been running them for 9 months now

 

[PWillette]

Where does it rub in the back? Would a different offset wheel cure that or cause new problems in the front? I’m looking at 2 offsets in the same wheel. +12 and 0. Not sure what to get.

Offset won't help in this case...there's a plastic wire protector that hangs down behind the rear wheels on both sides. I'm running +12 offset and it will rub this plastic full stuff. Some have just cut it off.

 

[nolimits]

Offset won't help in this case...there's a plastic wire protector that hangs down behind the rear wheels on both sides. I'm running +12 offset and it will rub this plastic full stuff. Some have just cut it off.

I might add, all else being equal I would take the +12’s over 0 offset. Less scrub radius if only minor.

 

[userdude]

37s seriously overwhelmed my Sasquatch coilovers…going to 4wp/procomp coilovers solved it…

You have a 2dr? If so, how much lift did you get?

 

[Squatch]

I just got some 37's this week so not a lot of time to judge, but these KO2 C rated tires are lighter than the 35" E-rated KM3's I had so it feels a lot better on the road. I did have to remove the front mudflaps since they rubbed the 35's so there was no way they would work with the 37's.

Just gotta say I love the look of those wheels. I got a clearance deal on some Methods, but that "soft 8 hole" look in machined or polished should have been a factory option or maybe Big Bend stockers.

I'm going back and forth between KO2s and KM3s. My KO2s have been great and they generally wear well.

 

[Fordified1]

Offset won't help in this case...there's a plastic wire protector that hangs down behind the rear wheels on both sides. I'm running +12 offset and it will rub this plastic full stuff. Some have just cut it off.

My plan was to get rid of that plastic thingy and tape and hide the harness when I do the body lift. I’m going to try just 1/2” of body lift and see how it goes. I do rock crawl, but won’t really beat on it until the new wears off lol. Still on the fence about wheel offset. I’m running 17x9 with +12 now. Ansen has some black slotted wheels now. In both 0 and +12 I believe.

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