I need Help with my tires :( (1 Viewer)

[AJM0617]

Hey guys, I bought a set of 33X10.50R15 BFG Mud Terrain KM2 about 2 months ago for my 92 LC with 3FE motor, and I really like the tires and the looks of it on my rig except driving on uphill roads and freeway gets really old quick with this tires. my 80 can barely keep up 60 mph on uphill parts of the freeway that's down shifted on 3rd gear :/ I did the tune up already with all OEM parts, and my timing is correct. lately I have been thinking about selling my 33's and go back to 31's... is 31's really the best size for 3fe powered LC? I need some advice here. I love the looks of 33's on my rig but It sucks on uphill.. also my full tank gas is 20 miles less now than when I had 31's. Should I just go back to 31's? I know I know it's a 3fe motor (will be slower than any car on the road)

Thanks in advance..

 

[BamaPaul]

Yeah your gonna be slower especially up hill. The only way to get your factory gear ratio back is to regear in some form or fashion. The 3FE has a power band that it likes to operate in and when you step up in tire size it lowers the engine rpm at any given speed putting it out of the proper range. The auto tranny in the fj80 eats up power through the torque converter so you could pull that out and throw a manual in there or you could put new gears in the front and rear diff. If you don't drive the interstate much then it shouldn't be a horrible problem.

 

[TCinVA]

Everything is a trade off. If you go bigger tires in a low powered vehicle, you need to regear to get back your performance. Once your truck is sitting taller and has more rolling resistance, your mileage will drop. If you mainly drive on the road, you might be better off with 31's. You could probably find someone looking to move up in size and trade back. Good luck!

 

[CJF]

D*mn, dude.

You had this HUGE thread where you kept saying how you reallyreallyreally wanted those tires.

And yes, 31's are best for a 3FE with stock gearing.

 

[Sc0-]

Turbocharge or regear the axles, 4.56 or 4.88R&P's

 

[retrofive]

Driving seat experience may be different because I've never driven one, but watching Jon Held wheel in Moab gave me a whole new idea of what a 3fe 80 can do on large tires.

 

[AJM0617]

D*mn, dude.

You had this HUGE thread where you kept saying how you reallyreallyreally wanted those tires.

And yes, 31's are best for a 3FE with stock gearing.

I did and I still like the tires, but the dropped performance especially uphill got old really quick (2 months) 31's look small on LC but I guess it performs better :/

 

[Pin_Head]

Learn to live with it.

 

[maybe_a_80...]

Learn to live with it.

I agree with Pin_Head on this one

 

[echotree]

Re: Your 20 miles less per tank and slower speeds. You're likely not getting much less mileage and you're going faster than you think.

31" tires are only 94% the circumference as 33" tires. That means your speedo is showing slower than your actual speed now that you have 33" tires. You're going about 5 mph faster than your speedo shows when it says you're going 70mph.

That also means that when you fill up, you should divide your trip odometer reading by .94 to get a good read on it. That will at about 20 miles to a 300 mile trip odometer reading. So you may not be getting any less miles per tank.

I just did this switch myself, and if my understanding is correct, the math works like this. (31 X 3.14159) / (33 X 3.14159) = 97.39 / 103.67 = .94

Use the .94 division trick to calculate how many miles you're getting per tank and the difference in mph.

60 mph speedo is (60 / .94) = Approx 64 mph.
300 miles on the odometer is (300 / .94) = Approx 320 miles.

Obviously, this doesn't take into account tread wear on the 31" or 33" tires, so everything is approximate.

I think.

 

[diego355]

Just deal with it its not that bad

 

[ironhippy]

just downshift, you'll be fine

 

[busmup808]

just downshift, you'll be fine

2x. I'm running 35 mtrs(5 total), ARB bullbar, Warn 8274, Crusin Offroad sliders and skid plate, rear drawer, fridge, & tools. All that weight running on stock 4:10 gears. I've learned to live with it for 3yrs.

If and when I'm coming to a hill, I just down shift to 3rd and all is good. If it's a long hill and the momentum fails, I just put my hazards on and watch everybody pass. Lol I'm regearing in the future, but I'm fine with it for now.

Sent from my hawn finga using IH8MUD

 

[Rwhat]

I bet you never been so happy to be behind the slow RV or big rig. Anticipate hills and put the pedal to the metal. Also try manually shifting the transmission.

 

[Florida 80]

Just save up and re gear. I love the 33s on mine, but I live in Florida, so I don't deal with the big hills all the time.

 

[AJM0617]

just downshift, you'll be fine

That's what I've been doing uphill on highway. But when people sometimes are too dumb and slows down to 40mph uphill for no reasons, and Of course i have slow down too, its really hard to get back to 55mph uphill.. oh well.. I plan on re-gearing in the near future anyway

 

[ironhippy]

Are you in first gear? Are you redlined?

No? then keep downshifting!

provided your truck/engine has been maintained of course.

 

[jonheld]

Driving seat experience may be different because I've never driven one, but watching Jon Held wheel in Moab gave me a whole new idea of what a 3fe 80 can do on large tires.

I have 4.88s in her and I run the 33x10.50 ATs on the street.
I think the key here is to make sure your motor is running as best as it can be. A valve adjustment can make a HUGE difference in power, along with making sure there are no top end vacuum leaks.
Make sure the EGR system is functioning as it should.

There is a laundry list of things that should be addressed on a 22 year old motor. Have a look at this thread:
https://forum.ih8mud.com/80-series-tech/270758-general-3fe-tune-up-info.html

 

[itbrokeagain]

I run 37s on stock gears right now. We have plenty of hills and I am able to do them at 65. Don't be afraid to downshift to second. It screams but it loves it. I do have 5.29 thirds reads to go in though. Can't wait for that