How many of you guys run LT tires?

[robfg67]

My MJ had LT265/75R16 tires on them when I bought it. I keep the tire pressure at 30psi, but the truck seems to run stiff and I suspect the thicker side wall is to blame.

 

I do occasionally load 700-1,000 lbs in the bed, but I'm sure passenger tires can easily handle that weight.

 

Thoughts?

 

[Pete M]

are they d rated or e rated?  stock suspension?  what shocks?  you can always drop the pressure a bit to experiment.  back when the MJ was my daily I ran 25 in the BFG ATs.   more recently I put LT rated tires on the old Durango (no change in size or pressures) and didn't notice anything different over the previous P-rated stuff. 

[robfg67]

E rated with a Rusty's 4.5" lift. 

[Pete M]

ohhhh.  lots of variables in there so it's hard to just blame the tires.  lift coils are notoriously stiff.  cheap lift shocks are notoriously stiff.  4.5" on short arms is notoriously stiff.   

[robfg67]

Pete, there's not a lot of great news in your answer.

 

[Pete M]

nope, but it is important news to know.   try dropping to 25 and see what happens. 

[robfg67]

I'll do that tomorrow and report back!

[coheed]

The BFG KO2s I have are the LT version. I can say switching to a spring with a better spring rate up front made a light years difference. I also switched from a OE replacement shock to a Bilstein 5100. I didn't notice a change in ride quality switching from the Falkens that were not LTs.

 

I've kept the psi at 30 throughout all the suspension changes. But I have a long bed and keep at least 200-300 extra lbs all the time over the rear. 

[robfg67]

Coheed...

 

1. Why did you choose LT instead of Passenger tires?

2. Where would I source front springs that have a better spring rate that would accommodate the 4.5" lift?

[Pete M]

we tow a bunch with the Durango (although the trailer is only half the rating of the durango) and I wanted a tougher tire after we had a tread separation of the P-rated tires on the way back from Florida.  I figure when the truck is doing truck things, it is a good idea to get a truck tire.   

[Limeyjeeper]

I have Toyo OpenCountry LT's on my Comanche. It rides great. However I have OME shocks. OME 160lb dual rate front springs and regular rear leafs. If I remember right

[coheed]

1 hour ago, robfg67 said:

Coheed...

 

1. Why did you choose LT instead of Passenger tires?

2. Where would I source front springs that have a better spring rate that would accommodate the 4.5" lift?

Well, the 31x10.5r15 BFG KO2 is only made as a LT now, though I liked the thought of being able to carry more weight. I carry scrap metal and motorcycles fairly often. Plus, the camper top and camping kit that stays on the back 70% of the time. I've carried reno demo loads for friends and new supplies with it as well. The tires have never changed how the handle or behave no matter how much weight I've put in the back. The KO2's are only a C load rating though, so a slightly thinner sidewall.

 

As far as springs go, most companies don't put out spring rates for their coils. Rusty's does and their 4.5" has a lower rate than the 3.5" RE coils I have. Pete is probably right that it may be the short arms or shocks.

[Htchevyii]

I've ran P rated tires. They are OK for mostly street use, (lighter weight can improve performance). Although they are less expensive, they often have half of the tread depth of an LT, thinner sidewalls and are much more likely to get punctured off road. I am running 4.5" springs with 1" spacers and the ride was brutal. The same components but with drop brackets improved the ride drastically.

[robfg67]

1 hour ago, Htchevyii said:

I've ran P rated tires. They are OK for mostly street use, (lighter weight can improve performance). Although they are less expensive, they often have half of the tread depth of an LT, thinner sidewalls and are much more likely to get punctured off road. I am running 4.5" springs with 1" spacers and the ride was brutal. The same components but with drop brackets improved the ride drastically.

Sway Bar or Control Arm Drop Brackets?

[robfg67]

Lowered psi to 25 and it rode a bit softer.

More to be done, of course.

[gogmorgo]

New tires are a lot of money, I don’t know if they’d solve your problem. We ran E-rated tires on Colorados on our work fleet because the trucks often drive on railway ballast, and that stuff eats tires alive. Stock size on otherwise stock trucks, at door sticker pressure. Doesn’t seem to affect the ride quality all that much.

 

For what its worth, LT vs P, or C, D, or E load range doesn’t strictly define a tire’s load carrying capacity. You want to look at load index. The LT tires are just more durable, more material is used in their construction. Thicker rubber, more reinforcing material. They’re heavier, and only marginally stiffer.

The load index is a two or three digit number followed by a lettre. The lettre is a speed rating. As an example, I’ve got some P tires as winters got my ZJ, they’re rated 112T, or 2469lbs per tire at 118 mph. This is of course way overkill for a ZJ but it’s slim pickings in the oversized winter tire market. In contrast my summers are an LT, C-range, but with a load index of only 109S, 2271lbs at 112mph. It’s also common to see more than one rating on a tire, usually a higher weight at low speed followed by a lower weight at higher speed, like 120Q/116S. 
And for what its worth, the owner’s manual for my ‘91 MJ only lists optional P sizes. No load index associated, but looking them up I’m seeing P tires in those sizes have load indexes at or around 100. I think you’ll have a hard time tracking down any tires at all in your current size that are rated anywhere near that low. 
You can also just look at the max load on the sidewall, compare it to your GVWR.

[Htchevyii]

9 hours ago, robfg67 said:

Sway Bar or Control Arm Drop Brackets?

Control arm. I wouldn't use sway bar drop brackets unless you had to, extended end links are better. I do have sway bar drop brackets because I'm running a steering box brace with a sector shaft support and they are needed to clear it.

[Pete M]

out of curiosity, what are you comparing the ride to?  it's not fair to compare it to a modern car. 

[jpnjake]

I run sagged 3” rusty coils (2” lift) with 3/4” spacers up front with super ride RE lca’s, and doetsch shocks in the front. In the back Hell Creek Metric Ton springs with RC shocks on 31” cooper evolution MT LT load range C. 
 

It rides a little stiff in the back while unloaded (40 psi in tires) But when loaded with between 400 and 800 lbs it rides like a Cadillac, soaks up dirt roads and potholes. 

Even unloaded the ride on dirt roads is surprisingly good. Even at highway speeds (70-85ish) it all rides very smooth, both loaded and unloaded with almost no vibration (with unbalanced tires)

 

Also the load range C tires are plenty for hauling and towing, you just need slightly higher pressures.

[JZLAJeep]

Not the tire expert here, but some empirical data. A while back I put LT tires on my stock 95 XJ and the tires lasted for 80K miles. They were sun rotting before they finally wore out. When they finally were getting sketchy for driving in snow I went back to the tire store, told the guy at the desk they ran for 80K and said I wanted another set. He couldn't believe that I had gotten 80K and had to come look for himself.  On my second set of those.

 

Lately I've been buying used LT tires on the other two Jeeps (because new tires cost more than the value of the vehicle) and have been having good luck with those.

[DesertRat1991]

18 hours ago, robfg67 said:

Lowered psi to 25 and it rode a bit softer.

More to be done, of course.

 

Just remember these are single cab pickup trucks.  Weight over F/R axles is not the same. You'll want to keep an eye on the tire wear patterns and adjust tire pressures accordingly.

 

I've found 28psi in front and 24psi rear works well for how I'm loaded down most days.

[robfg67]

22 hours ago, gogmorgo said:

New tires are a lot of money, I don’t know if they’d solve your problem. We ran E-rated tires on Colorados on our work fleet because the trucks often drive on railway ballast, and that stuff eats tires alive. Stock size on otherwise stock trucks, at door sticker pressure. Doesn’t seem to affect the ride quality all that much.

 

For what its worth, LT vs P, or C, D, or E load range doesn’t strictly define a tire’s load carrying capacity. You want to look at load index. The LT tires are just more durable, more material is used in their construction. Thicker rubber, more reinforcing material. They’re heavier, and only marginally stiffer.

The load index is a two or three digit number followed by a lettre. The lettre is a speed rating. As an example, I’ve got some P tires as winters got my ZJ, they’re rated 112T, or 2469lbs per tire at 118 mph. This is of course way overkill for a ZJ but it’s slim pickings in the oversized winter tire market. In contrast my summers are an LT, C-range, but with a load index of only 109S, 2271lbs at 112mph. It’s also common to see more than one rating on a tire, usually a higher weight at low speed followed by a lower weight at higher speed, like 120Q/116S. 
And for what its worth, the owner’s manual for my ‘91 MJ only lists optional P sizes. No load index associated, but looking them up I’m seeing P tires in those sizes have load indexes at or around 100. I think you’ll have a hard time tracking down any tires at all in your current size that are rated anywhere near that low. 
You can also just look at the max load on the sidewall, compare it to your GVWR.

Thanks for all the info on tire load index. I think that I'll stick with LT's because I do carry some heavy loads.

[robfg67]

21 hours ago, Pete M said:

out of curiosity, what are you comparing the ride to?  it's not fair to compare it to a modern car. 

Great question Pete.

 

I've driven lots of different vehicles over the years, including work trucks and work vans. My MJ is much worse than almost any of them-although I was in a well worn Ford Escape once that rode like a cement truck.

 

I've gone under the truck and there is nothing that sticks out as an obvious loose or worn suspension part. The frame is solid, but it rides stiff and there are some unusual noises when going over rough roads-especially when turning.

 

I think that I'll find a shop that specializes in off road suspensions and pay for a diagnosis. I can change the parts myself.

[robfg67]

5 hours ago, DesertRat1991 said:

 

Just remember these are single cab pickup trucks.  Weight over F/R axles is not the same. You'll want to keep an eye on the tire wear patterns and adjust tire pressures accordingly.

 

I've found 28psi in front and 24psi rear works well for how I'm loaded down most days.

Good point. I'll do a chalk test on the four tires to determine the best tire pressure.

[robfg67]

On 8/20/2023 at 9:26 AM, Limeyjeeper said:

I have Toyo OpenCountry LT's on my Comanche. It rides great. However I have OME shocks. OME 160lb dual rate front springs and regular rear leafs. If I remember right

LimeyJeeper,

 

2 things...

 

I just read the entire 16-page build thread on your orange LS MJ this past weekend and all I can say is Wow, congratulations.

 

I just visited the OME website and I didn't see any products for the MJ. Did you just select Wrangler JK parts?