brulaz

Mine are wearing fine at 50-60psi, over about 30K miles so far.

When I first put the Michelin LTX MS/2s on, the dealer only pressured them up to 35 psi, the number on the door jamb for the original P's. I couldn't believe it because if you look at their tire inflation table, that gives them less weight bearing capacity than the original P's.

Then I checked with Michelin and they agreed. After asking what the original tires were and what they were inflated at, they calculated that to match the original weight carrying capacity of the P's, I should inflate the LTEs to a minimum of 48 psi. So I go for 50-60psi as I like the crispness. I don't go much higher as I don't know what pressure the wheels are rated for.

Maybe there was some legal/liability reason why the original dealer wouldn't inflate the LTEs over 35psi, but it was stupid, and they lost a customer.

xcntrk

I run E-rated tires and air them up to 60F/65R psi when towing. When I know I won't be towing for a while, I drop them down to 45/45 for a smoother ride.

Tystevens

Funny, my tire dealer pumped them up to about 80. The truck rode like a buckboard on the way home, I went back and he said well, you can go down to 60, I guess, but why install the LTs in that case ...

I'll probably just leave 'em at 55. It isn't bad, and I'm used to it, but I definitely noticed the rougher ride after I had them installed.

smokeywren

Use the load/inflation table for your size tire to decide. If the load range C tire has enough weight capacity at 50 PSI, then you don't need the heavier/stiffer load range D or E. But don't ignore load range D - that may be the compromise you need.

I have worn out several sets of Load Range E tires dragging my 5er around the USA with an F-250. But for dragging my lighter TT, I no longer need load range E to give me enough tire weight capacity to handle the wet and loaded F-150 with the TT tied on. And load range C seems to be a non-starter. They have less weight capacity @ 50 PSI than my Michelin P-series tires have @ 44 PSI. I now have 45,000 miles on my P-series tires, with about half those miles towing trailers that grossed from 1,900 to 6,100 pounds, and one 350-mile tow with my 8,000# 5er. The 5er severely overloaded that F-150, but exceeded the rear tire weight capacity by only 69 pounds (3%) per tire. I checked the tire temp often with a laser temp gun and they never got hot. No problems on that trip, but knowing how much overloaded the poor F-150 was, I wouldn't want to do it again.

Another overloaded trip with no problems was moving Darling Daughter, dragging my "bumper pull" cargo trailer from El Paso TX to Ontario OR with 700 pounds tongue weight and 8,020 GVW on the two truck axles (GVWR 7,100). Gross trailer weight was 6,100. 13,420 GCW, so less than the 14,000 GCWR. The truck bed was loaded for bear with a queen-size bed including mattress, frame, dresser mirror, and other stuff covered with a Leer cap. The drive axle grossed 4,740 compared to the 3,800 rGAWR. Rear tires were overloaded by about 100 pounds per tire.

But again, pumped the pickup tires up to 44 PSI, and pumped the load range E trailer tires up to 65 PSI, and checked regularly with the laser temp gun and everything was cool, and no tire problems on that long trip.

But anyway, for me load range C would be a dumb move, I don't normally need load range E, and my P-series tires are just about perfect for my needs to tow a cargo trailer that usually grosses less than 5,000 pounds or a TT with a GVWR of 5,600 pounds that has never grossed more than 5,000 pounds.

acadianbob

My observations:
* Gas mileage does go down when switching from P's to LT's. Heavier tires means more unsprung weight and mass to rotate
* The ride does degrade
* I've been running 40 pounds empty with my LR C's and they wear nice and even.
* LR C more than covers my payload capacity. Why go to E's that you don't need, that ride harsher, the get worse fuel mileage.
* The LR C tire does make for a better towing experience compared to the P's.

I have a buddy with an F150 equipped like mine except that he has P's. Noticeably better ride in his truck.

nfrank

If I were to stick with the P rated tire, is there one that is better than the other as far as not being so squished under load? I figure about 1,100 lb tongue weight and another 400 lbs people and gear when I take the camper out. Even with max inflation they look and I think they feel squishy.

I'm considering replacing with either P, LT C, LT E 275/65R18 Goodyear All-Terrain Adventure.

BassAckwards

Unless your P-Metric tires is an XL or RF (Extra Load, Reinforces) they don't hold any weight beyond 35psi. Anything above that is strictly for speed ratings. So unless you get a P-Metric meant to hold more weight than no, not really and there aren't any options for that in our size to be honest. You're better off getting a LRC tire.

smokeywren

That didn't make sense to me, so I researched a bit further.

TRA load/inflation table shows P275/65R18 load index 114 (2,601 pounds), speed rating T (118 MPH), load type SL (standard load), and UTQG (Uniform tire quality grade) 420 A B to have a max weight capacity of 2,601 lbs. at 35 PSI. But the specs for that tire as well as the sidewall markings say the max weight capacity is 2,601 and the max inflation pressure is 44 psi.

So for that exact tire, you're right in that PSI over 35 does not add weight capacity. 2601 is the max weight capacity whether the PSI is 35 or 44 or somewhere in between.

But I have about 20,000 towing miles on my P-Series tires with no problems, so I'll continue to pump the rear tires up to 44 PSI when towing.

Of all the tires in size P275/65R18 sold by TireRack, none are load type XL They do have some load type XL tires, but none in the sizes we need.


Go to TireRack.com and search for size P275/65R18 and you see that most of the P-Series tires have a load index of 114 (2,601 pounds). But there are a few with load index of 116 (2,760 pounds). Here's one:
http://www.tirerack.com/tires/tires....omCompare1=yes

Nope. Max load is 2,535, which is less than the P-Series standard load tire of the same size.

BassAckwards

I was more referring to if he just absolutely wanted a LT tire he could go with LRC which would handle all the weight he could carry and not hit his gas mileage and ride quality quite as bad.

nfrank

I'm not worried much about going over weight in my tires. I'd be way over weight on the axle before that and have bigger worries. I'm just looking for something with better performance.

I ran the LR Es on my previous truck ('01 Tundra), but this F150 has a much harsher ride. I wish I could just try on the tires like shoes.

I think I'm leaning towards P tires and since inflating them every time I tow is a hassle, just get a 12v compressor.

I drive about 20k miles/yr. about 3k towing.