Tires are getting old... time to make some decisions
- Thread starter COS80
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How do you know they're hardening, some cracks appearing?
Perhaps your rig is parked outside and/or the tires have a lot of miles on them because this seems like premature wear to me. I've had 20 year old tires that showed no cracking!
COS80
SILVER Star
- Thread starter
- #23
No cracking yet. They're old, per the date code. The thumbnail tells me they're harder than all the other tires I have. I believe the PO parked it outside.
On my last snow run, my copilot, without any clue this was going on, told me he could see and feel my tires were getting old, by the way they lose all traction in an instant (he's been off roading for 40+ years).
My wife drives my 80 on 37s all the time. It drives pretty normal on 4 inches other then the sway, as the truck self removed the front sway bar 10 years ago. If the truck is set up properly it should drive pretty good. No you don’t swerve to miss the deer or elk, you square them up and hit um, I made that clear to my wife, don’t try and do quick movement just run over and slow down as much as possible and hit the thing, truck has bumpers let them do some work.
I’ve killed two 80’s. The first was on an OME basic lift running 315’s on stock wheels. I was snow wheeling and slid over a steep bank and rolled twice in 2015. The second was after having ran 37’s for six years back in the spring of 2023. I was goofing around up in the National forest near my house and tipped over at about 25 mph. Being the mud tires stuck out past the body the sidewalls gripped the ground and she came back up on the wheels minus the windshield but I was able to drive her home. Rollover number one was was definitely not the fault of 37’s. Number two may have not happened with your current set up, probably not. However, both were my fault not the fault of vehicle set up.
If you do the set up properly and do all the necessary supporting mods and then drive accordingly there should be no problems. Something else to consider is that braking distances will be a bit longer but many members have realized improved braking after removing the old abs system even on larger tires myself included.
At this point it seems to make sense that you buy 35’s, and, if necessary install some spacers, on top of the springs. Then regear to 4.88 with the option to install transfer case under drive gears later if you do go to 37’s. It’s not a good idea to run a tire as long as possible if you are an off-roader. I’ve seen tires rip in half at less than 5 years old. I run them about four years and replace them even if there is still plenty of meat left. Some one will give you a few bucks for the take offs. With that in mind, during the 4 years you run the 35’s you’ll have time to spread out the purchasing and installing of some of the supporting mods for those 37’s. This is much less painful and requires little to no negotiations at the dining room table.
Like @mudgudgeon said, lockers, 35’s and a GOOD winch will get you any where 37’s will but with perhaps a little more finesse.
One thing my wife did appreciate about our 80 going up to near 5” lift and 37’s is that there was a lot less boobie shocking impacts of the frame down onto boulders. This could be a great negotiating tool…….. keep us posted.
mudgudgeon
Resident galah
Instinct for most says otherwise.
I t-boned a car last year (other driver was 1000% at fault), and I know better, but braced for impact and bent the steering wheel about 2½inches
Box Rocket
SILVER Star
I'll share a bit of my experience with this topic. My last 80 was a '93 that I bought with a 2.5" lift and 35's. The lift height change a few times but it always had 35's and always had stock gears and was a daily driver for 15+ years. The stock gears and 35's never really bothered me except on some of the long, steep canyons like Parley's canyon east of Salt Lake City. So depending on where you do most of your driving you might be just fine with new tires and leaving the rest as is. You could definitely fit 35's with your current lift. If you're driving a lot of mountain passes or other climbs then the regear might be more important to go with the tire size increase.
My current 80 was on 35's and stock gears for a couple years before I finally regeared to 4.88's. The 4.88s definitely helped on longer highway climbs but I didn't love how the truck drove. The shift points seemed off and the truck would hunt for the right gear on the highway a lot. Then I switched to 37's. 37's and 4.88's are a near perfect match to stock gears and stock tires so the shift point are back in the right spots and overall driveability is much better IMO. Some people love 4.88's with 35's and 5.29's with 37's but I'm not one of them. I prefer the 4.88's with 37's and would suggest transfer case reduction gears for lower offroad gearing.
On the topic of 37's, you can fit 37's with 3" lift for street driving pretty painlessly. But if you want to wheel it you'll be in for a decent amount of effort to get it right. You can always keep the tires from rubbing with bumpstops but that solution can also limit your suspension travel which would be a net loss in performance IMO. To me the point of bigger tires and maybe a slightly taller lift is to help improve offroad performance. If the result of fitting those bigger tires means I lose suspension travel then I don't see the point. You'd be better off with 35's and more suspension travel IMO. So, if you want to keep all the suspension travel (or at least reduce it as little as possible) then you'll definitely be doing some trimming, tuning the bumpstops, and might need to play around with different wheel offsets and the tires you choose to get a setup that tucks well without a lot of rubbing. That's the path I took. I took me a bit to get it all dialed but I was able to maintain a full 12" of front suspension travel, 13" of rear travel. I had to modify the Timbren bumpstops that I have to get the height just right to minimize tire rub and not kill suspension travel. An area I could probably still improve is the wheel/tire combo. I chose to force myself to trim a bit more by having wheels with a slightly wider stance. So some of it is going to come down to what you want to keep most. If perfect sheetmetal is your priority, then plan on limiting suspension travel with bumpstops. If flex is most important, then you might have fewer wheel options and you'll probably need to do some trimming. etc.
Radius arms and rear control arms will obviously affect fitment too. I used radius arm relocation brackets to move the front axle ( which solved the most egregious tire rubbing that was at the rear of the front wheel well when the tires were turned lock to lock). I switched out the bolts that hold the fender skin to the inner fenders to button head screws so the tires wouldn't catch the sharp edges of the bolt heads. I also rolled the inner fender lip on the rear fenders so the tires would tuck into the wheel wells better. So most of my trimming was just to the inner edges of the flares.
Last thought....
unless you're really planning to hit the tougher trails most of the time you're wheeling then I'm still of the opinion that a 3" lift and 35's is the sweet spot for an 80. Easily done with bolt on parts and fitment just works without much extra effort/cost/parts. The truck is still very capable even on difficult trails and will only struggle on the more extreme stuff. That's it for my opinion and experience from 25+ years of owning/driving an 80 that has never had tires smaller than 35's.
My current 80 was on 35's and stock gears for a couple years before I finally regeared to 4.88's. The 4.88s definitely helped on longer highway climbs but I didn't love how the truck drove. The shift points seemed off and the truck would hunt for the right gear on the highway a lot. Then I switched to 37's. 37's and 4.88's are a near perfect match to stock gears and stock tires so the shift point are back in the right spots and overall driveability is much better IMO. Some people love 4.88's with 35's and 5.29's with 37's but I'm not one of them. I prefer the 4.88's with 37's and would suggest transfer case reduction gears for lower offroad gearing.
On the topic of 37's, you can fit 37's with 3" lift for street driving pretty painlessly. But if you want to wheel it you'll be in for a decent amount of effort to get it right. You can always keep the tires from rubbing with bumpstops but that solution can also limit your suspension travel which would be a net loss in performance IMO. To me the point of bigger tires and maybe a slightly taller lift is to help improve offroad performance. If the result of fitting those bigger tires means I lose suspension travel then I don't see the point. You'd be better off with 35's and more suspension travel IMO. So, if you want to keep all the suspension travel (or at least reduce it as little as possible) then you'll definitely be doing some trimming, tuning the bumpstops, and might need to play around with different wheel offsets and the tires you choose to get a setup that tucks well without a lot of rubbing. That's the path I took. I took me a bit to get it all dialed but I was able to maintain a full 12" of front suspension travel, 13" of rear travel. I had to modify the Timbren bumpstops that I have to get the height just right to minimize tire rub and not kill suspension travel. An area I could probably still improve is the wheel/tire combo. I chose to force myself to trim a bit more by having wheels with a slightly wider stance. So some of it is going to come down to what you want to keep most. If perfect sheetmetal is your priority, then plan on limiting suspension travel with bumpstops. If flex is most important, then you might have fewer wheel options and you'll probably need to do some trimming. etc.
Radius arms and rear control arms will obviously affect fitment too. I used radius arm relocation brackets to move the front axle ( which solved the most egregious tire rubbing that was at the rear of the front wheel well when the tires were turned lock to lock). I switched out the bolts that hold the fender skin to the inner fenders to button head screws so the tires wouldn't catch the sharp edges of the bolt heads. I also rolled the inner fender lip on the rear fenders so the tires would tuck into the wheel wells better. So most of my trimming was just to the inner edges of the flares.
Last thought....
unless you're really planning to hit the tougher trails most of the time you're wheeling then I'm still of the opinion that a 3" lift and 35's is the sweet spot for an 80. Easily done with bolt on parts and fitment just works without much extra effort/cost/parts. The truck is still very capable even on difficult trails and will only struggle on the more extreme stuff. That's it for my opinion and experience from 25+ years of owning/driving an 80 that has never had tires smaller than 35's.
mudgudgeon
Resident galah
Great summary.
Its easy to overlook what these trucks are capable of, and talk yourself into mods with little net gain, and a lot of money and time spent getting there
COS80
SILVER Star
- Thread starter
- #32
Im here, at the end of my tire life, because I pretty quickly realized the truck was far more capable than me (I'm new to this game), so I kicked the upgrade can at least until the tires it came with were shot. I have encounter a number of fails that bigger tires would have helped me with, just as recently as last weekend (plowing deep snow with the axle doesn't work so well).
There's a thread on here about what you would differently if you started over again. Lots of people said they wish they would stayed lighter and gone with less lift and tires. Some, far fewer as I recall, said they wish they had just gone big to start with. Just a thought. Good luck with your rig and tire selection.
Here's the link: If I was to start all over again, I would... - https://forum.ih8mud.com/threads/if-i-was-to-start-all-over-again-i-would.884004/
Here's the link: If I was to start all over again, I would... - https://forum.ih8mud.com/threads/if-i-was-to-start-all-over-again-i-would.884004/
Last edited:
COS80
SILVER Star
- Thread starter
- #35
This "Stage 1/Stage 2" idea is gaining traction. After all, it's about safety!
Thinking a 35X12.50R17 on a wheel optimized for the 37x12.50R17 would be smart, because then, in a few years, I can just change tires.
I could save a few bucks now and do a 315/75R16 on my current SCT wheels, but I believe that would require a spacer, yes? I don't know a thing about spacers, but it looks like the choice is 1.25" or 1.5".
So my questions are:
Thinking a 35X12.50R17 on a wheel optimized for the 37x12.50R17 would be smart, because then, in a few years, I can just change tires.
I could save a few bucks now and do a 315/75R16 on my current SCT wheels, but I believe that would require a spacer, yes? I don't know a thing about spacers, but it looks like the choice is 1.25" or 1.5".
So my questions are:
- For the 37x12.50R17, what's the ideal width and offset/backspace?
- For the 315/75R16, I assume the 1.25" spacer would be plenty. True? I have to verify my wheel specs, but I believe they 16X8et0.
77mustard40
SILVER Star
mudgudgeon
Resident galah
And down the rabbit hole you go.
315/75r16 on a stock rim or rim with the same back spacing should work with 2" lift.
Add spacers or a rim with less back spacing/ more offset and you increase the scrub radius ( google it) and potential for rubbing on full lock. And less room to tuck the tire under the fender.
You gain more clearance to the frame and radius arms.
On my hzj105, 315/75r16 rubbed on the frame on stock 8" rim.
On 8" run with 1" offset ( more backspace) the tire rubbed on the floor pan footwell, rubbed on the rear edge of the front fender, rubbed on the washer bottle inside the fender. Rubbed on the lip of the rear fender.
Add 37" tires and the scrub radius increases more. More likely to rub. . .
Cue the bumpstop mods. Fender cutting etc
mudgudgeon
Resident galah
There's a bunch of trial and error unless you find someone who had thoroughly documented their build, and copy their build as faithfully as possible.
posted above somewhere, just changing to a different tire can upset a sorted setup
posted above somewhere, just changing to a different tire can upset a sorted setup
