Making sense of Tire Load Rating and Load Index?

[21F150_208]

I am going to be running a payload of 60% of max in the Summer and am advised to get a tire with a D or E load rating. Meanwhile, I'm looking at tires with a load index of 114 or 116.

Why not just use one measurement? Load Index appears to be more widely used in tire specs.

It seems like D load rated tires are 8 ply, and E load rated tires are 10 ply(?) The weight carrying capacity difference between 114 and 116 is 2601 lbs versus 2756 lbs.

Once I get past this load topic I'll look at off-road v road and expected terrain. As long total load carry is less than GVWR beyond ride & gas mileage aren't we good to go?

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[UGADawg96]

The load index in LT (E) tires varies based on PSI. They may be 2400 at 45lbs, but 3400 at 75lbs.

Look here:
https://tirepressure.com/lt285-60r20-tire-pressure

Whereas on passenger tires, the load index is much more constant anywhere between 30 psi and 40psi

 

[PBXL]

As a brand new full size truck owner myself, this is an area of great confusion. I can only share my personal experience so take it for what it is worth.

I swapped my stock tires out for LT tires because I knew I wanted to be towing once in a while. I don't know what LT stands for, but my guess is Light Truck? Anyways, LT so far seems synonymous with E rated tires, which I learned are good for towing. If you choose to go with LT or E rated tires, then the next area of confusion is what PSI to run. Big O tires put 35 PSI cold in my LT tires. This is what is in the drivers door for cold PSI recommendation. This lowered my MPG by 2-3. After reading multiple forums on the internets, I pumped up my tires to 45 PSI. This is the highest PSI I have ever put into any tires, so I was pretty hesitant. I thought my tooth fillings would shake loose while driving. Luckily, this has not been the case and the ride quality is still very good at 45 PSI cold and my MPG went back to normal as well. I also towed a 5000 lb trailer at 45 PSI and everything was great.

 

[21F150_208]

Thank you! I've never considered running a higher PSI.

 

[aika1]

I am going to be running a payload of 60% of max in the Summer and am advised to get a tire with a D or E load rating. Meanwhile, I'm looking at tires with a load index of 114 or 116.

Why not just use one measurement? Load Index appears to be more widely used in tire specs.

It seems like D load rated tires are 8 ply, and E load rated tires are 10 ply(?) The weight carrying capacity difference between 114 and 116 is 2601 lbs versus 2756 lbs.

Once I get past this load topic I'll look at off-road v road and expected terrain. As long total load carry is less than GVWR beyond ride & gas mileage aren't we good to go?

Oh my, this is a big can of worms.
LT tires are "light truck", yes. They come in C, D, and E in the most common designations for passenger trucks, and go higher for trailer tires (F, G, H, etc.). Back in the day it related to a ply rating (c had 6 plies, d had 8 plies, and E had 10 plies). That is no longer the case. Now MOST of those tires have the same number of plies, and the letter designation of E corresponds to a weight rating that roughly equals that of a 10-ply tire. Get it? still 2-3 actual plies, but the tire's weight carrying capacity is equal to an old 10-ply rating from back in the day.
LT tires work differently than P-rated tires (stands for Passenger). P-rated tires are built to hold a weight relatively without regard to PSI. LT-rated tires are built with a varying weight capacity, based on the PSI currently used. so a LT-E is rated for a maximum of ~2700 lbs at say 80PSI. it is NOT rated at 2700LBS at 40PSI. It is rated for significantly less at that 40PSI.
Where that comes in handy is when you want to air up your tires for a large load (heavy trailer or payload), you can, and when you want to air down for a smoother ride (with LT tires, less PSI means a "softer" carcass that's more forgiving), you can do that for ride comfort.
A LT-C will ride softer and smoother than a LT-E tire. LT-E's are common on 3/4 trucks as standard equipment. They are typically NOT on 1/2-ton trucks like the F-150's because the weight is low enough on the truck that an LT-E will ride stiffly. I worry about that if/when I lift my truck and may have to go to an LT-E for size.
Oh! and LT tires typically weigh more for the size tire when compared to P-rated tires, have more tread depth, and many do not come with a treadlife warranty (50k miles warranty, etc.).

I hope this gets you started!

 

[DBL R]

For those of us who tow only a few times a year, a p-rated tire with adequate max load rating “should” work?

arbitrary numbers: a truck with payload of 1,500 lbs and a trailer weighing 6,000lbs with p rated tires that have a 2,600 lb load rating. Approx 400 lbs for occupants, 10% hitch weight so approx 600 lbs hitch. Those would come out to approx 1,000 lbs total. So within payload and we’ll within the 2,600lb load rating of the tires. So with these arbitrary numbers one could easily tow without requiring LT tires? Is my math right or am I missing something here?

 

[Roscopcoletrain]

with my previous trucks, I used to go with a E/LT tire. When I got my Sierra, I went with an XL (Xtra Load) tire. Sorta in between a P and a LT. They worked good, and I'd say for part time towers, a good choice.

 

[21F150_208]

Oh my, this is a big can of worms.
LT tires are "light truck", yes. They come in C, D, and E in the most common designations for passenger trucks, and go higher for trailer tires (F, G, H, etc.). Back in the day it related to a ply rating (c had 6 plies, d had 8 plies, and E had 10 plies). That is no longer the case. Now MOST of those tires have the same number of plies, and the letter designation of E corresponds to a weight rating that roughly equals that of a 10-ply tire. Get it? still 2-3 actual plies, but the tire's weight carrying capacity is equal to an old 10-ply rating from back in the day.

Oh! and LT tires typically weigh more for the size tire when compared to P-rated tires, have more tread depth, and many do not come with a treadlife warranty (50k miles warranty, etc.).

I hope this gets you started!

I never knew that one should inflate E rated tires to 75 or 80 psi until I started down this path. I thought the yellow sticker in the door jam was to be followed at all times.

I ended up getting E rated tires that were 48 lb each - most seemed to be in the 60+ lbs range. I'm making up a bit for the PowerBoost payload loss with lighter tires.

Like everything else, I wanted a different look that what I bought, with tires sold by my tire shop, that were e-rated, at a great price. It was a pick any three of the four kind of deal. I've owned the brand I bought for decades and gotten 80,000 miles out of a prior set, so I'm happy. Thanks for a very helpful post.

 

[aika1]

I never knew that one should inflate E rated tires to 75 or 80 psi until I started down this path. I thought the yellow sticker in the door jam was to be followed at all times.

I ended up getting E rated tires that were 48 lb each - most seemed to be in the 60+ lbs range. I'm making up a bit for the PowerBoost payload loss with lighter tires.

Like everything else, I wanted a different look that what I bought, with tires sold by my tire shop, that were e-rated, at a great price. It was a pick any three of the four kind of deal. I've owned the brand I bought for decades and gotten 80,000 miles out of a prior set, so I'm happy. Thanks for a very helpful post.

The sticker in the door is for tires that came on your vehicle, specifically the TYPE of tire. So if your rig came with P-rated tires, follow that sticker as long as you stay with P-rated tires of the same size. Going to an LT? that sticker goes out the window and trial-and-error becomes your friend. Some folks will air up a few PSI for longer trips and better mileage (run more on the middle of the tire) or for heavy loads that will distort the tire. Lower PSI for comfort...

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