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Wondering what it takes to run 37” tires? Picture included

Keith73bronco

Newbie
Joined
Mar 21, 2017
Messages
6
I know there has been post about this before. But I was wondering what it would take for me to run 37” tires. I have a 3.5 inch suspension lift and a 2 in body lift. The bronco has a np435 backed with an atlas 2 with 4.10 gearing. I just want to know what I should do to safely run the 37s. You can see the pictures of the bronco on my profile picture. I haven’t figured out to put one in the post I’m running 33” as of now . Thanks
 

73azbronco

Contributor
Bronco Guru
Joined
Nov 11, 2007
Messages
8,049
I was wondering what it would take for me to run 37” tires.

37? Balls of steel my man.

Seriously though, what motor you running? I think they should fit with what you have, but....4.1 is on weak side for 35's let alone 37's. Unless you have a motor to back that up. I have no issue with 35's as I'm pushing a 347 through an NV4500, so lots of gears to chose from.

Need to be a contributor to post pics.
 
OP
OP
K

Keith73bronco

Newbie
Joined
Mar 21, 2017
Messages
6
Sorry I forgot to mention is a fairly stock 302 with mild rv cam. I’m would definitely be re-gearing. Maybe 456s or lower. But that’s part of the question what would work best with the 37s. I’m trying to get a list of this to do before I get the tires. Other options was go with 35s witch the bronco had on it when I got it and it drove pretty well. And crawled pretty well also.
 

bchesley

Full Member
Joined
Dec 21, 2012
Messages
327
You have everything you need. The atlas gets you the low gears off road and the 4 speed should get you moving fine. I am running 37's with 4.56 in the axles, stock 302, C4 and stock dana 20 and it does great. I would of course love to have the atlas as the icing on the cake though. As far as lift goes, I am sitting 2 inches less than you are and don't have any issues either. See photos.
 

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SavageBurro

Sr. Member
Joined
Aug 12, 2013
Messages
589
What ratio is the atlas? Do u still wanna be able to cruise at 60+? 4.56 w 37 and np435 are decent for top speed without too high rpm but lack a bit in all around seat of pants power. 5.13 would be better for all around but not as great on hwy. Depending in atlas ratio I'm sure it will crawl excellent.

Other items to consider: massage inner fenders, maybe bump stops, stronger shafts and joints, hydroboost brakes, reduced turning radius solved w spacers or curved radius arms (spacers add leverage not great for safety), grab handles to get in, high quality steering pump w cooler maybe ram assist if offroad, stronger than stock steering linkage, brace frame at ps box...
 

sprdv1

Contributor
REBEL
Joined
Mar 8, 2007
Messages
81,961
Sorry I forgot to mention is a fairly stock 302 with mild rv cam. I’m would definitely be re-gearing. Maybe 456s or lower. But that’s part of the question what would work best with the 37s. I’m trying to get a list of this to do before I get the tires. Other options was go with 35s witch the bronco had on it when I got it and it drove pretty well. And crawled pretty well also.

running 4.88s w/that same set up.. some trimming required if you do some good wheeling..
 

sprdv1

Contributor
REBEL
Joined
Mar 8, 2007
Messages
81,961
You have everything you need. The atlas gets you the low gears off road and the 4 speed should get you moving fine. I am running 37's with 4.56 in the axles, stock 302, C4 and stock dana 20 and it does great. I would of course love to have the atlas as the icing on the cake though. As far as lift goes, I am sitting 2 inches less than you are and don't have any issues either. See photos.

same here, other than 4.88s... does great for most part off road

low tire pressure in back, and winch down front to squeeeeze it in garage haha
 

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JohnJohn

Contributor
Bronco Guru
Joined
May 6, 2005
Messages
2,161
Loc.
Richmond
4.56 or lower is highly recommended for 37"s. You will want to upgrade to hydroboost brakes. Rear disk is not going to help as much as hydroboost will but both are recommended.
I have a bronco with 35's, 4.10 gears, C4 and disk front and could not lock them up with the stock vacuum booster until I added hydroboost.
I also have a bronco with 37's, 4.56 gears, C4 and disk front and could not lock them up until I added hydroboost.
 

Seventee

Contributor
Sr. Member
Joined
Dec 7, 2012
Messages
997
Loc.
In the sticks of MT
How much highway driving do you do? I would definitely go with 4.88 with my NP435/302 setup, but I rarely am on the highway and when I am I don't drive >65mph anyway.
 

Apogee

Bronco Guru
Joined
Nov 26, 2005
Messages
6,103
My build will be similar, but with 65" F150 axles, so about 6 inches wider, otherwise it has 3.5" SL, 2" BL, 351W/NV4500/ATLAS 3.8/4.88 drivetrain. My fenders are cut about like bchesley's above just under the body line, though with the wider axles it looks like I'm going to need to take a little more out of my front fender and possibly bottom of the grill...I'm mid-swap on the HP D44 at this point, so I haven't gotten to flex it out yet in the real world.
 

TN1776

Bronco Guru
Joined
Oct 24, 2006
Messages
2,632
I run 4.5" coils up front, 5.5" leafs out back, 2" body lift and 37" tires. I had to limit my up travel in the front a lot. I have the WH warflares all around and I don't have issues rubbing the outer fenders. I have issues rubbing the inner fenders hence the bump stops. I cannot imagine being able to run 37" tires on less lift, though some people seem to get away with it.
I run 4.11 axle gears, and up until recently an NP435 and D20. In 4th gear, 65mph is 2500 RPMs which isn't horrible, but I am used to my other vehicles cruising at or below 2000 rpms at that speed in overdrive. I am converting to a ZF for the overdrive now. My 351 isn't exactly a fire breathing monster but it's able to bark the rear tires on dry pavement from a stop. I don't see a need for lower axle gears personally. I am further reducing my crawl ratio with an Atlas if it ever arrives...
 

NateMob

Full Member
Joined
Jul 24, 2011
Messages
248
I would love to see what everyone is doing with their inner fenders up front, especially with the stock battery location.
 

Madgyver

Contributor
Bronco Madman
Joined
Jul 30, 2001
Messages
14,801
just get the tires and mount them... regear after or during install whichever fits your situation..
 

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