P rated vs LT rated tires

alpnst · Jan 24, 2017

I know this has been debated before, but I don't think I have seen the answer i am looking for.

I have a 2014 Ram Sport 4x4 CC 5.7ft bed with the 3.92 gears. According to RAM that puts my tow rating at 9,850 pounds and 1,300 cargo capacity. The stock Goodyears have a rating of 2,601 pounds per tire for a total of 5,202 pounds and the truck has an axle rating of 3,900 pounds.

So it is clear that the factory tires far exceed the axle rating, however everyone here seems to think that if you are going to be towing a trailer you need LT tires. BFG A/T KO2's for this truck would only have a rating of 3,000 pounds per tire or 6,000 total, but an added 40 pounds of rotational weight for worse gas mileage and acceleration.

Please explain to me why a P Rated tire is not adequate.

Thanks,

MM

reindeerman · Jan 24, 2017

First you need to multiply the BFG A/T KO2's rating by four.

On my past 3rd generation truck I changed from P series to LT's and yes you can feel the difference. I tow a lot and the LT's make quite a bit of difference. Less sidewall flex means a lot when your wagging thousands of pounds behind you. More responsive steering and less sway.

I'm currently running BFG A/T KO2's on my 4th generation and expect they hurt the fuel mileage. Can't tell because they were new when I bought the truck used. I get crappy MPG when towing anyway.

Devin1349 · Jan 24, 2017

I've towed with the stock P rated tires with the load was fine there was a bit of pudge in the sidewall but that was expcected. from what ive read if i were to inflate my tires to about 40psi there would have been less bulge and was informed that it would ride smoother.

alpnst · Jan 24, 2017

reindeerman said:
First you need to multiply the BFG A/T KO2's rating by four.

.

Why? I am strictly taking one axle rating, but if you want to talk two axles then the math would be as follows.

Stock tires 10,404 pounds rated. Total axle rating 7,800 pounds.

BFG A/T KO2 12,000 pounds rated. Total axle rating is still 7,800 pounds.

In both scenarios the tire rating is higher than the axle rating.

DannyMK2 · Jan 24, 2017

anybody who has put a decent load in or behind their truck can tell you their is a major difference and the stock tires suck for towing. if all your going to do is look at numbers, then your stock tires are more then adequate.

alpnst · Jan 24, 2017

DannyMK2 said:
anybody who has put a decent load in or behind their truck can tell you their is a major difference and the stock tires suck for towing. if all your going to do is look at numbers, then your stock tires are more then adequate.

My question is not exactly about stock tires. I am just using them as an example. I actually am looking at the Dynapro ATM's which have the same load range as stock and the Nitto Terra Grappler's that have an extra 155 pound more per tire rating.

I am trying to understand while everyone says it is unsafe to tow with P rated tires when the numbers all fall within a safe rating. No one is answering that question.

DannyMK2 · Jan 24, 2017

alpnst said:
My question is not exactly about stock tires. I am just using them as an example. I actually am looking at the Dynapro ATM's which have the same load range as stock and the Nitto Terra Grappler's that have an extra 155 pound more per tire rating.

I am trying to understand while everyone says it is unsafe to tow with P rated tires when the numbers all fall within a safe rating. No one is answering that question.

its been answered already. the sidewalls are not as stiff on a p rated tire vs a LT tire. is it technically unsafe, no. im sure going to a better passenger tire is an improvement over the stockers, but i would say most people skip over that and go straight to a LT tire to avoid any remorse, not to mention the fact that most tire sizes in the 33"+ range are already LT anyway.

Devin1349 · Jan 24, 2017

I don't think its the fact that P rated tires are unsafe, if they were why would ram use them in the first place know well enough that the truck is built to tow haul. now my two cents is that others might be advising tires that are safer than stock tires. so you can tow within your regulated towing capacity but for a safer ride look at after market. if you get what im saying

billyw · Jan 24, 2017

P rated tires need to be derated by 10 percent in truck applications too. So they're not quite as potent as you think. However, if aired up all the way, they usually do the job just fine. But if you're towing at all heavy, let's say a big travel trailer, in windy conditions or you need to make quick steering adjustments, the LT tires will tend to keep you firmly planted, where the P rated might be a little squirmy before completely responding. I like the comfort of knowing that if I hit a curb or pot hole while towing, the LTs are likely to survive better too.

6.7CumminsDrvr · Jan 24, 2017

^^^^^^^^^^that right there! Look up load inflation table and read up.

alpnst · Jan 24, 2017

billyw said:
P rated tires need to be derated by 10 percent in truck applications too. So they're not quite as potent as you think. However, if aired up all the way, they usually do the job just fine. But if you're towing at all heavy, let's say a big travel trailer, in windy conditions or you need to make quick steering adjustments, the LT tires will tend to keep you firmly planted, where the P rated might be a little squirmy before completely responding. I like the comfort of knowing that if I hit a curb or pot hole while towing, the LTs are likely to survive better too.

The way I read the tables is that you need to de-rate the tire by 10% if going to a P-rated tire from an LT-tire. Meaning if your truck was shipped with an LT and you wanted to use a P-rated tire it needs to have a greater load rating stamped on it so when it is de-rated it matches that of the LT tire. Is that not the case?

So it looks like everyone is the opinion that an LT rated tire is better because of the stiffer sidewall and not because of the load index.

billyw · Jan 24, 2017

Tire Tech Information - Load Reduction of Euro- & P-Metric Tires on Light Trucks

billyw · Jan 24, 2017

LT tires likely require higher inflation pressure too. If they don't have enough air, they can suffer heat damage due to sidewall flex.

smiley · Jan 24, 2017

LT tires gain puncture resistance which I have enjoyed over the years. Even when I got something in one of my BFG tires it did not even make it into the tire far enough to puncture it was just in the tread face.

jasonw · Jan 24, 2017

If you go one size up from factory on the 20 inch rims, to 275/65R20, LT tires are about all you can find.

I went that route because I want a truck to ride a little more like a truck, and the extra plies are nice to have for towing and puncture resistance, as smiley said above. Only real downside (unless you want a softer ride) is the extra weight of the LT tires, which equates to lower MPGs, especially at highway speed.

reindeerman · Jan 24, 2017

alpnst said:
Why? I am strictly taking one axle rating, but if you want to talk two axles then the math would be as follows.

Stock tires 10,404 pounds rated. Total axle rating 7,800 pounds.

BFG A/T KO2 12,000 pounds rated. Total axle rating is still 7,800 pounds.

In both scenarios the tire rating is higher than the axle rating.

You asked the questions and I answered. And you had your math wrong.

Sorry you didn't like it like it!

Well over one hundred thousand mile towing. How many miles have you?

huntergreen · Jan 25, 2017

the factory uses P rated tires for a more comfortable ride. if you are towing heavy and far, you want the LT tire for the stiffer sidewall which gives better control when needed.

sbarron · Jan 25, 2017

huntergreen said:
the factory uses P rated tires for a more comfortable ride. if you are towing heavy and far, you want the LT tire for the stiffer sidewall which gives better control when needed.

The factory uses P-rated tires because they meet their specifications and are cheaper that LT tires. They also only use P-rated tires on specific models which statistically marketwise are less likely to see heavy towing/hauling or off-road use without modification.

If someone is looking at a rig for towing, hauling (working) you aren't typically looking at the models that come on shiny 20" wheels to begin with. You might even pass on the entire 1500 line which renders the whole P-metric vs LT tire argument moot.

gofishn · Jan 25, 2017

alpnst said:
My question is not exactly about stock tires. I am just using them as an example. I actually am looking at the Dynapro ATM's which have the same load range as stock and the Nitto Terra Grappler's that have an extra 155 pound more per tire rating.

I am trying to understand while everyone says it is unsafe to tow with P rated tires when the numbers all fall within a safe rating. No one is answering that question.

Oh, it is safe but that is not the be all end all of the towing experince. P rated tires have more sidewall 'give' than LT tires. This gives feels like a squishinees andcanexagerate things like body roll or trailer sway causing ruck to swa and feel squirrelly.

LT tires removes all of that.

Negative of LT tire is the tendancy to overload the truck beyond the limits of the C-clip axle and the corresponding damage that can result.

alpnst · Jan 25, 2017

reindeerman said:
You asked the questions and I answered. And you had your math wrong.

Sorry you didn't like it like it!

Well over one hundred thousand mile towing. How many miles have you?

How is my math wrong? I already stated I was talking about one axle and I added the 2nd axle in a previous post. Even if we add in in the de-rated factor for a P-rated tire both it and an LT-tire exceed the axle capacity of the truck.

I don't keep a log of miles towed so I am not going to get into a ******* match with you, but I have plenty of miles under my belt with SUV's, light trucks, and heavy duty trucks.

P rated vs LT rated tires

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