My 2013 FX4 came with 20" Pirelli ATR's that were P rated. I got 55K miles out of them without any problems, but it's time for a new set. Is it best to stick with P rated tires or is it better to go with LT?

55k out of those isn't bad. P's are only good for city and highway driving no heavy loads. If your doing any off road go with the LT's.

Load Index

P195/60R15 87S - The load index (87) is the tire size's assigned numerical value used to compare relative load carrying capabilities. In the case of our example the 87 identifies the tires ability to carry approximately 1,201 pounds.

The higher the tire's load index number, the greater its load carrying capacity.

89 = 1,279 pounds
88 = 1,235 pounds
87 = 1,201 pounds
86 = 1,168 pounds
85 = 1,135 pounds

A tire with a higher load index than that of the Original Equipment tire indicates an increase in load capacity. A tire with a load index equal to that of the Original Equipment tire indicates an equivalent load capacity. A tire with a lower load index than the Original Equipment tire indicates the tire does not equal the load capacity of the original.

Typically, the load indexes of the tires used on passenger cars and light trucks range from 70 to 110.

I do believe you got some stuff mixed up.

What do you use the truck for?

Towing a boat and driving back and forth to work you will be fine with p-rated tires just like you were for the last 55k miles.

If you drive off road and worry about thorns rocks etc. the lt's would be a better choice, but I put 50k on my factory P-rated tires between work and a south texas ranch with decent roads and never had a flat.

The p-rated tired on the truck are rated for more weight than you should be putting in the truck. I towed 8k lbs on p-tires, I wouldn't put them on a hot shot rig, but just because you pull a 30-foot TT twice a year doesn't mean you need to put E-rated tires on your truck. P-series are significantly cheaper and if they do what you need there is nothing wrong with them.

corrected, I'm getting dyslexia in my old age.

Call me crazy...but I swear I get more miles out of tires that have a heavier load rating. LT at a minimum.

I'd call you crazy if you said it made monetary sense to buy LT's over P's. Ive gotten pretty close to the same mileage with a slight nod to the LT's on similar vehicles, but the LT's are significantly more spendy.

I'm mostly highway driving and pull the boat a couple of times a month. I'll go off road a few times a year, but usually in Nebraska where it is more dirt than rock. I do drive in the snow up there though and drive a few gravel roads. The original tires were Pirelli Scorpion ATR P275/55/R20 111S. I've been looking at the Nitto Terra Grappler G2s or just stick with Pirelli's.

I tried the Terra Grappler G2's for a weekend, they were pretty quiet, smooth as silk, had pretty good traction and were priced pretty good. I opted for the Trail Grapplers although just because I get into mud more than sand or snow. You wont be disappointed with them. PLUS they have a 50k limited warranty...

you will be disappointed in mud with the Nittos. Tread is not open enough. The Nittos would be go for the OP. Sounds like he does not use 4wd much. I had a set of Pirellis on my 2001 F150 that barely made 27k. I would not recommend to anyone.

Stump Jumper - what do you recommend? And you're right, I don't use 4wd very often. Probably 6 or 7 times in 2.5 yrs.

Also take into consideration that if you go with LT tires they are a much stiffer ride than the P rated tires. Normally LT rated tires come on f250's and up. Id stick with P for what you are doing.

You are thinking load range Es. If the OP goes with a C he will be fine.

Same here.

if you rarely get in the mud then look for a closed tread Nittos, Bridgestone, and Cooper all make an AT that has a tight tread. Smaller voids will be quieter on the highway. Look for a load range C. Also look at Michelins and Goodyear silent armor if you don't mind spending more.