E rated tire with max psi of 65?

[BurbMan]

I have Nitto Ridge Grapplers that came on the truck when I bought it used, size LT325/65R18 E 127/124Q.

Every E-rated tire I've ever seen is rated to carry its max load at 80psi, so the first trip out with the camper I didn't even look at the tire, I just aired up to 80. Back home 1000 miles later and I see on the sidewall that the max rating for the tire is 65psi.

Sure enough, the Nitto site says may rating is 3860 lbs@ 65 psi. Anybody ever hear of an E rated tire running at 65 psi max?

These are way oversized for the truck (spec calls for minimum 9" rim width, mine are 8"), but after running them on the highway at 80 psi, then on the beach at 20 psi, and at 55 psi unloaded, the truck handles great and wet weather traction/stopping is at least as good as the Revo 3's I had on the Burb.

I was looking for a reason to get rid of these but haven't found one yet....these are about 50% worn, and next set will be the same maybe a size smaller.

[MFL]

FYI, Grit dog, your posts are still not showing up till much later!

This one, below, took nearly two days. It likely was flagged, due to off topic, and your sometimes off color posts, many that I enjoy.

Grit dog wrote: Sometimes it’s time to stop arguing mfl...

Your last two posts, while interesting, are still a bit off topic, and may be reason for screening? I know...I'm off topic of thread subject right now. I do have to say that the OP did get his question answered, and even sent a PM to me, saying he appreciated my opinion. Nice fellow, always has good info to share!

I've been on this forum long enough to know whose info/opinion I would choose to follow. The internet is great, anyone can be who ever they pretend to be, or not! I don't consider you to be FOS (your words, not mine), but some folks tend to be more gullible than others.

PM me if you want to discuss further. I don't want to join the red flag list!

Jerry

[Grit_dog]

And he said that's what Les Schwab recommended since they couldn't hit the 80psi rear recommendation on the door sticker of the truck!


Of course they did! If I sold tires, I'd want people replacing tires as often as possible. Sounds like they are achieving their goal as well!

[Grit_dog]

MFL wrote:

Grit dog wrote:
Sometimes it’s time to stop arguing mfl...

Not arguing with you Grit, just added the reminder of misinformation you may have forgotten from the other member.:C

Cheers back at ya,

Jerry

Cheers to you too bud!
This whole discussion, not unlike many on here revolves around both facts and opinions. But the real difference of opinion, IMO, is...
Is information "bad" information if it doesn't completely idiot proof it for anyone reading it regardless of their personal skills, experience or competency?

Large MFGs "have" to idiot proof their products to the greatest extent possible, even if it means something not being ideal or the best for a given situation (classic case in point, the STUPID tire pressure monitor thresholds on 3/4 ton trucks). This was mandated by the NHTSA I'm sure, but point is, that it's wrong for all but a certain set of conditions.
No different than Capri's or my advice which is also correct for a certain situation and wrong for others.
My personal feeling is that anyone of average intelligence "should" be diligent enough to figure out basic things like the right tire pressure, but I have a great example of why this isn't the case.

Recently acquired a used truck, sitting on 37-12.50-20 tires. The previous owner, by all accounts is a very intelligent and mechanically inclined young man, as he is an engineer tech and supervisor at a machine shop and also a gear head.
He had the (fairly new and very expensive) tires on this truck set to basically the max pressure of 65psi on the front and 60 psi on the rear. The he was killing the tires, hurting the ride of the truck and actually driving with "less" traction than if he had the proper pressures. Tires new 19/32" tread. Fronts were 19 on the shoulder lugs and 16-17 in the middle. Rears were 18-19 on the shoulder lugs and 14-15 in the middle.
And he had NO clue that this was happening, nor that they didn't need that much air.
Fortunately, it's early enough I can bring these tires back into shape, but I never would have expected it out of this guy.

[MFL]

Grit dog wrote:
Sometimes it’s time to stop arguing mfl...

Not arguing with you Grit, just added the reminder of misinformation you may have forgotten from the other member.:C

Cheers back at ya,

Jerry

[Grit_dog]

Sometimes it’s time to stop arguing mfl...

[BenK]

Burbman...your sand compacts better than the stuff I normally run on.

The sand am used to would NOT leave such distinct tread pattern. It would fall apart, unless wet.

Wonder why east coast sand isn't rounded by eave action as much as out here on the west coast.

The 'apparent' diameter am talking about will on additional tread contact in length. Measured at the leading to trailing tread contact. That is more important, but bulge width and cupping also plays.

The minimual tread penetration on your current tires look very good, considering loaded with that camper n stuff.

Cleaning out the garage attic and found my old surf rods. Gave them away except for my first rod I made as a teen.

Fenwick fast taper and has been rebuild several times. About 12-13 feet with extra long handle and larger diameter cork.

Mainly strippers with occasion gulls hitting the metal spoon (Mickey Mouse, with a hulla skirt)...

[MFL]

BurbMan

While I am not experienced driving a heavy vehicle in that type sand, it appears that your psi choice is leaving a proper foot print. The pics are interesting, worth a thousand words! 🙂

Jerry

[MFL]

MFL wrote:

Good to see where your info comes from. While there are many types of tires, if you would have taken the time to read the link Burb posted, it is a hybrid type (dual purpose) tire, that by design, would work best, considering sidewall and tread at 65 psi. Other tires purpose will vary, and while e-rated, may also be less than 80 psi

CapriRacer wrote:

"Ah .... That's not how it works."

MFL wrote: JUST YOUR OPINION

All forums are full of opinions!! Seldom are these backed up with facts. In the past, you have posted info that would cause a dangerous condition for someone taking your advice, while towing a heavy trailer. Due to lack of knowledge, you suggested airing TV rears to door sticker (35 psi), even though tire stated max was 50 psi. Yes, I know, the correct info may not have been available in the book at hand. This is where someone's opinion with actual experience matters more.(this info for Grit Dog, concerning his statement of your info always correct) Yes, GD also knows better, from actual experience!

Lots of things to consider for a dual purpose tire, including compounds, softer/firmer, longevity over function, etc.

Lol..."heat is a tire killer"

Is there anyone on this forum, that does not know this...no book necessary!!

Capri...I am not trying to discredit your being a tire tech! Just saying, that like me, you, and others, none of us have the absolute last word on any subject.

While the OP did over inflate his tires, carrying a heavy load (camper) on tires too wide for his rims, it may have kept them cooler, with less squirm. May have improved handling? In any case, my opinion, and from experience, a proper sized tire for the rim size, is best choice.

Jerry

[BurbMan]

BenK wrote:
Burbman...I’d go down in width and go to a higher aspect ratio (Larger number, which is the percentage of section width) for your setup. A higher profile tire’s sidewall will help when you go to the beach and that sand those beaches are famous for.

Hey Ben good to hear from you! The issue with taller aspect ratio is overall diameter of the tire....if you look at the spec chart, a 295/70-18 is significantly taller than stock.

I was out on the beach one time this year in early November for a trial run. Missed most of the beach season due to camper reconstruction. I aired these big tires down to 20 psi (I was going to 15psi with the 265/75-16's on the Burb) and took this pic...I am a size 13, so my foot measures about a foot...



Much wider footprint than the burb tires. Also bear in mind that the burb with the TT attached was about 8600 lbs, this rig with the camper is about 11,600 lbs.

Can't wait to get out there again

[JIMNLIN]

grit wrote:
And we’ve all had experiences we learned from.
I learned about the right width rims for tires and right pressure for treadwear at the same time, same truck, 1 set of tires.

Very true.
Other folks,mine included, experience with proper tire width/wheel width come from a haulers perspective carrying max or close to max axle/wheel loads on trucks and trailers 24/7 for 70k-90k miles a year. Many times its two sets a year on the truck and the trailer. So proper wheel width for the tires tread width means more trouble free/best handling/more miles down the road.
Big oversize wide 65 psi tires didn't give the best service/mileage/handling for any of five trucks in my huge :B five truck fleet.

So yeah we apply our personnel experience(s) in many choices.

[CapriRacer]

MFL wrote:
...... While you SAY burst pressure the reason, then add that burst is many times the max pressure, it would seem that 80 psi rather than 65 psi, would not cause burst. .....

What's really going on here is fatigue strength. Wikipedia: Fatigue (material)

Tires are all about fatigue and in order to design a tire to go through 10's of millions of cycles (rotations), the designers uses the burst pressure as a reference and then uses a factor to increase the strength to get the desired fatigue life - which they get from an S-N Curve for the material in question.

So while tires don't burst at 80 or 100, or 150 psi, that burst pressure is an indicator as to the fatigue life.

MFL wrote:
Good to see where your info comes from. While there are many types of tires, if you would have taken the time to read the link Burb posted, it is a hybrid type (dual purpose) tire, that by design, would work best, considering sidewall and tread at 65 psi. Other tires purpose will vary, and while e-rated, may also be less than 80 psi. ......

Ah .... That's not how it works.

The simplest way to describe this is to say:

1) that the WORST condition is the onroad condition, because heat is the tire killer! So the fact that we are discussing an onroad/offroad tire still means the onroad condition is what the tire engineer has to design against.

2) that the tables were set up (over 80 years ago!) so that a construction for a given Load Range works for all tire sizes - which means that when a tire gets to a certain size, it can't withstand the stress, so the Load Range drops down to the next lower increment - in this case from 80 psi down to 65 psi.

[BenK]

X2....N-Trouble’s comment/thoughts

Following is more rhetorical than anything...why are folks so hung up on a tires PSI rating...when most diss the GVWR/GCWR/MTWR/etc ratings ?...and recommend that they don’t really matter...

Selective adherence to ratings IMHO...

Most get away with that mentality & recommendations because designers have dialed in some level of margin (AKA...safety margin as most think it is). How much they dialed in and how much management told them to remove is a guessing game or more aptly lucky that they haven’t found where that line is...


Off soap box...


Burbman...I’d go down in width and go to a higher aspect ratio (Larger number, which is the percentage of section width) for your setup.

A higher profile tire’s sidewall will help when you go to the beach and that sand those beaches are famous for.

Airing down will have a higher profile tire’s sidewall ‘bulge’ more, which forms both a ‘wider’ footprint...and many don’t know that the tread will also ‘cup’ inwards, which helps ‘catch’ more sand and NOT slip as much. The higher the aspect ratio (higher number, or higher percentage) will allow the sidewalls to collapse more.

Also, with a higher profile tire aired down, the ‘aparent’ tire dia will be much larger than a lower profile tire. Around some old campfires, buddies and I noodled and came to a consensus that our tires were in the effective +8 foot diameter range.



Finally, note that squared off tread to sidewall transition area needs to be rounded. Street tires with a much more squared off (sharp transition) will dig better in soft stuff (dirt, sand, etc)

Edit...for those who don’t know...airing down is for very slow going ONLY.

If you plan to drive above, say, 10MPH with aired down tires...that will shorten your tires life greatly.

Go faster and you may not make it back to pavement with the tires in good condition.

[N-Trouble]

mich800 wrote:

twodownzero wrote:
I wouldn't get rid of them. I have the Ridge Grapplers on one of my trucks, not one I use to pull or carry a camper, and they've actually been great tires. I would, however, not air them up so much unloaded. Check your door panel for what the original tires used for pressure and back that down some. 35-40 psi is probably more than enough.

The inflation sticker is only applicable if running the size/spec tires the sticker is referencing.

Why cant people figure this out? Especially dealers and service centers. Check the freakin sidewall NOT the truck

Wider tires (generally 285 and above) will be 65psi max. A wider footprint tire doesnt need as high an air pressure as a narrower tire to support the load. This is nothing new. Been this way for years. Has nothing to do with on/off road.

[Grit_dog]

@Burb.
I’d say 285-75s or 295-70s would be more ideal based on your OE rims.
And that’s about the point where capacity maxes out without going to 12” range width tires which “should” have wider rims.
FWIW, I ran 275-65-20s last set on the 07 Ram with OE 20” Ram wheels. Mainly because I’m cheap and that size isn’t so popular and $200/tire was hard to pass up for Firestone MTs. Those were all that was needed to hold up the white whale on the old Dodge. So know that you can get by with anything from the 275s on up.