Tire aspect ratio

[agesilaus]

I got a new to us 2018 Ram 6.7L 2500 and it is mostly great. But it came with Sailun mostly worn out tires 275/R70 18 tires. Escapees right now have a fantastic discount on Michelin 275/R70 18 tires at $105 off each tire. My understanding is that R75 means 70% or the height of the tire and R65 means 65%. I assume that not a problem. The ones I'm looking at are Michelin P275/65R18 114T LTX AT2 DT LTX AT2 at $245 discounted

[mkirsch]

agesilaus wrote:
?? you're saying a LT275/70R18 cannot be E rated? Why not?

If you were replying to me, no.

I am saying a "P275/70R18" tire cannot be E rated. E is a rating for LT tires, not P tires.

Your first post stated that the "P" tire was rated load range E, as quoted.

To further complicate the issue, tires are now all rated with a "Service Description" regardless of P or LT. This consists of a load index and a speed rating, a three digit number (or two) and a letter.

https://simpletire.com/learn/tire-buying-guides/tire-service-description

[Grit_dog]

agesilaus wrote:

Grit dog wrote:

agesilaus wrote:
?? you're saying a LT275/70R18 cannot be E rated? Why not?

You’re confusing yourself even more. That size tire IS predominantly made in E load models.
However eliminate all confusion of LT vs whatever, ply rating , letter designation and just use load index if you’re having trouble understanding the other more generic classifications.

I am not confused, I was uninformed but that was taken care of 10 or 12 posts back, and you have not explained that strange claim about 275 tires. But I see the post was edited to add a P to the 275

Then maybe I'm confused....(not about tires, jsut about your understanding). You just asked the question I replied to, 3 posts back...:S lol
And there are not strange claims...tire load ratings are about as black n white, objective and qualitative as something can get.

[agesilaus]

Grit dog wrote:

agesilaus wrote:
?? you're saying a LT275/70R18 cannot be E rated? Why not?

You’re confusing yourself even more. That size tire IS predominantly made in E load models.
However eliminate all confusion of LT vs whatever, ply rating , letter designation and just use load index if you’re having trouble understanding the other more generic classifications.

I am not confused, I was uninformed but that was taken care of 10 or 12 posts back, and you have not explained that strange claim about 275 tires. But I see the post was edited to add a P to the 275

[blt2ski]

If the size has an "LT" in front of it, it's a light truck rated tire. It can have a C-6 ply, D -8ply, or E-1ppky rated tire. The C will have a lower capacity than a D, D is lower than an E.
If a "P" is in the front, that is the lowest payload rated tire if it can fill to 32_36 psi. Their is an XL version, that can handle 45 psi. That tire is more like a C rated tire in capacity.

So as grit mentioned, unless you look at the actual load ratings, you won't know if the tire has the ability to carry the load you need.

In my tire size, an E can carry 3700+ lbs per tire. A P/XL tire 2500 lbs per. This is a 1000 lbs over my spring capacity. 2 XL tires could carry my truck fully loaded at 7200 gvwr door sticker wise. Issue I have, is the size ONKY comes in 10pky E rated tires. I'm over tired bt 2x capacity.

Marty

[Grit_dog]

agesilaus wrote:
?? you're saying a LT275/70R18 cannot be E rated? Why not?

You’re confusing yourself even more. That size tire IS predominantly made in E load models.
However eliminate all confusion of LT vs whatever, ply rating , letter designation and just use load index if you’re having trouble understanding the other more generic classifications.

[agesilaus]

?? you're saying a LT275/70R18 cannot be E rated? Why not?

[BenK]

IMO...boils down to whether a person believes in the OEM specifications or not

If yes, then follow them and things like warranty will apply

If no, then do whatever and things like warranty may not apply...unless that person lies about following the specification...

[mkirsch]

agesilaus wrote:
LTX A/T 2 Tire
Light Truck, SUV/Crossover All Terrain
P275/65R18
Load Capacity 3640 Pounds
And below it says load range E
But that is for the 275/65

And Michelin makes a
Size: LT275/70R18 125/122S E
Style: Blackwall
Load Range: E
Serv. Desc: 125/122S
UTQG: None

So I don't know why it's not shown. I'll call tomorrow

A P275 tire would not be rated "Load Range E."

So you're mixing your metaphors here...

[MFL]

Go Grit...right on, even 3/4 example! While de-rating, of wrong tires, can be needed, why bother, just get the proper tires, and done.

Jerry

[Grit_dog]

^Great, but the OP needs LT tires.
PS , I’ve heard the de-rating nonsense on here for years. It’s laughable. Akin to 1800lb payloads in 3/4 ton trucks. Just regulatory nonsense.

[BenK]

Maybe folks will accept this link to TireRack’s page on P vs LT class tires and the reference to the RMA recommendation of de-rating P class min 9% when used on pickups & SUVs

LOAD REDUCTION OF EURO- & P-METRIC TIRES ON LIGHT TRUCKS

edit...fixed clicky https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=70

tirerack wrote:
When it comes to selecting replacement tires for a van, pickup truck, crossover and SUV, the most important consideration is to maintain sufficient load carrying capacity.

Three tire-sizing systems are used on the Original Equipment (O.E.) tires fitted to today's light trucks, Euro-metric, P-metric ("passenger" metric) and LT-metric ("light truck" metric). Many 1/4-ton and 1/2-ton vehicles use Euro-metric and P-metric sized tires, while 3/4-ton and 1-ton vehicles use LT-metric sized tires.

Euro-metric and P-metric tire sizes were originally designed for cars and station wagons; however, they have also been used for light truck applications because most vans, pickup trucks, crossovers and SUVs are used to carry passengers, not cargo. Additionally, most of the new light trucks being produced today are equipped with Euro- or P-metric sized tires because they offer lighter weight, lower rolling resistance and less aggressive tread designs (which makes them better riding, more fuel efficient and less noisy) than typical heavy-duty tires.

However, there is an idiosyncrasy governing the use of Euro-metric and P-metric sized tires on vans, pickup trucks, crossovers and SUVs because these vehicles have a higher center of gravity and greater probability of being overloaded than passenger cars. In order to accommodate this, vehicle engineers are required to specify Euro- or P-metric sized tires rated to carry 10% more weight than would be required if they were used on a passenger car. This is the equivalent of taking the tire's load capacity branded on its sidewall and dividing it by 1.1. For example, a Euro- or P-metric tire designated to carry 2,000 pounds on a car is restricted to carrying 1,818 pounds when used on a van, pickup truck, crossover and SUV. This size selection practice provides the vehicle manufacturer with the appropriate tire load capacity.

On the other hand, LT-metric sized tires were specifically developed for use on light trucks and provide the full tire load capacity branded on their sidewall. They are the little brothers of the heavy-duty tires fitted to 18-wheelers and buses, and use the same basic engineering guidelines regarding load capacity. Because of this, LT-metric sized tires are built very strong, and use higher inflation pressures to carry a given load in order to provide the desired safety margin. You really don't want the tires of the 18-wheeler alongside you on the interstate running at the limit of their endurance, do you?

While there isn't a problem determining an appropriate alternate size when replacing Euro- or P-metric tires with other Euro- or P-metric sizes, the differences in load capacity and required inflation pressure prohibits mixing the LT-metric tires with Euro- or P-metric tires, as well as often prevents replacing sets of Euro- or P-metric tires with dimensionally equivalent LT-metric tires, and vice versa.

Selecting the correct tire size will help ensure you have the performance and long term durability you desire.

[Sport45]

Michelin is a bit deceptive with the name of this tire. The LT in LTX doesn’t mean anything as “LTX” is just the name of the tire, no different than “Wrangler”, “Discoverer”, or “AT3”. As mentioned above, go by the load index and look for LT preceding the section width on the tire size.

[agesilaus]

I was somewhat confused but aware that something did not seem to be right. Which is why I asked here in the first place.
However I will disagree about the 'cheap tires', these Michelin's are over $350, the Escapee discount knocks $105 off the price making them look cheaper.
I was hoping for a combination of Michelin road reputation, and occasional off road driving. Especially looking for that extra mpg that Michelin has a reputation for in these parlous times.

[Cummins12V98]

Grit dog wrote:
Another train wreck of mis information, over explanation and stories about that “one time I….”
Do you all have ADD???

OP, you found cheap tires that are P rated and 114 load rating. This is obvious by the load rating. There is no further question. You have confused yourself about tires.
Use a tire that is rated properly for the vehicle it is to be installed on. Pick the size pick the brand pick white letters or not, but don’t install anything with less than a 121 load index.

Folks that's that!!!