SL/P vs LT rated tires discussion

[UGADawg96]

my F150 is currently running 20 inch wheels wrapped in 35 inch “F Load Rated” tires.
my Ram 1500 is currently running 20 inch wheels wrapped in 33 inch “SL Rated” tires.

if i’m driving drive the same exact road that i always take i notice that i feel every single characteristic of the pavement in my Ram as opposed to my Ford. is this just because my tire sidewall profile is thinner on the Ram or more like an air pressure issue?

Maybe the universe is just saying ditch the Ram and get another Ford

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[richardrocks]

I wish “legendary” KO2s came in SL load rating in my size for the better ride and ability to simply inflate based on the door placard. I’m currently running 41 PSI but BFG says that 50 would be appropriate for towing at truck’s capacity.

Falken AT3Ws came in SL but I must have gotten a defective set because after some washboarded roads they rode horribly and rebalancing didn’t help.
At least I’m getting better sidewall protection

 

[fordhouston]

I just went through this. I went from factory P Hanook's to E General's ATx to SL Nitto's RG. The main reason, to get a lighter weight tire. The instant I drove away from Discount Tire on the Generals, the truck was notably slower to accelerate (3.31 gears), heavier steering/handling and rougher ride. I air up all my tires with 38 to 40 PSI. I tried several air pressures with the Generals, no dice. So back they went and I switched to an SL rated Nitto RG 305/55R20 116Q 2756 lbs. at 44 PSI. Night and day difference over the E tires. Acceleration was back, handling/turning was back, ride was back, love them. I typically tow a #5000 equipment trailer or a #4000 21' boat, and I haven't noticed any difference whatsoever, not even swaying

The way I look at is Ford didn't put E on my truck. I could be wrong but I think I read the non-HDPP rear axle is rated to #5000 So why do I want a tire that exceeds the weight carrying capacity of the truck. One reason as mentioned above, sidewall strength. So when you do load up or have a heavy trailer, the truck doesn't sway back and forth as much. I did the sway test with my Generals and then my Nittos but I was hard pressed to see one tire sway more than the other. I suppose if you air up an E rated tire to 80 PSI it would be rock (Flintstone mobile) and not give at all

I also read "no no no, you need an E tire if you do any kind off roading, even a gravel driveway" There is a big write up in 4-Wheeler on the pros and cons of E rated tires for off roading that says otherwise...

Any way, just my $0.02 and hope it helps.

what PSI are you currently running for your Nitto’s?

 

[TexasTruck]

what PSI are you currently running for your Nitto’s?

38 PSI cold front and rear.

 

[Aron]

my F150 is currently running 20 inch wheels wrapped in 35 inch “F Load Rated” tires.
my Ram 1500 is currently running 20 inch wheels wrapped in 33 inch “SL Rated” tires.

if i’m driving drive the same exact road that i always take i notice that i feel every single characteristic of the pavement in my Ram as opposed to my Ford. is this just because my tire sidewall profile is thinner on the Ram or more like an air pressure issue?

If your tires aren’t inflated to the proper spec, they’re going to absorb most of the road irregularities. F-load tires are intended to be inflated to about 90psi. If you’re running F-load tires at P-load inflation ratings, they’re basically almost flat. It’ll feel like a better ride, but it may damage the tire and it’ll significantly increase the rolling resistance, which will reduce your fuel efficiency.

This explanation may help the discussion:

https://blog.tiremart.com/tire-load-range-and-ply-rating/

 

[powerboatr]

this is not 150 specific
but....my bus came with goodyear g series tires specifically built for RV market, you know wear out fast, hard to keep balanced etc
these are big tires OTR type tires ran fronts at recommended psi for weight on tires , 100 psi
still wore out side and rivered across tread because they would not stay balanced so at 12k miles they were taken off
put on hankook otr tires same weight rating of 6k lbs per per tire, more sidewall belts and one extra tread belt, ran same psi 100 in fronts, these tires do have a 130 psi rating vice the 120 for the good years, but they are pressured based on weight chart
balance beads, etc... tires ride 1k times different. no weird wear, and a smoother less HARSH feedback over bumps
so i agree each tire company rides different , even at same psi setting
and i have air ride all around.

tire places should offer up a ride test on prospective tire purchases to see how they ride compared to what the customer is looking for

and always run tires at pressure that correspend to the tire weight vs psi chart to get a smooth across tread wear pattern , while maintaining good ride qualities and length of service times

 

[Aron]

Another thing that I just remembered regarding high load range tires is that not all wheels are capable of withstanding such pressures. Before inflating to high pressures, you should verify that your wheels won’t be damaged.

I’m assuming that one could find such information on the internet if one looks hard enough. I’ve also heard that many wheel producers will stamp their ratings on the inside of the wheel, but I’ve never dismounted a tire to verify that.

 

[MillstoneF150]

LT275/65/20 E-rated Firestone Destination XT at 35-40 psi ride better than stock 275/60/20 SL Hankook Dynapro AT2 at 35-40 psi. The biggest difference I noticed is that the rear doesn't "dance" or "hop" over bumps anymore. The tires are absorbing the impact and not the suspension (or lack of absorption due to no weight in rear) as much in that scenario.

 

[Tosh]

Another thing that I just remembered regarding high load range tires is that not all wheels are capable of withstanding such pressures. Before inflating to high pressures, you should verify that your wheels won’t be damaged.

I’m assuming that one could find such information on the internet if one looks hard enough. I’ve also heard that many wheel producers will stamp their ratings on the inside of the wheel, but I’ve never dismounted a tire to verify that.

The OEM Lariat 18" wheels that came with my truck are marked DOT E
The OEM tires are Goodyear Wranglers (LT?) and I'm now running Falken Wildpeaks (E).
My impression is that the Wildpeak tires (38 psi) are firmer but not harsh or bouncy. The Wranglers felt a little to soft for my taste, even at 38 psi.

However, say good bye to 24MPG with those heavier tires.....

 

[fordhouston]

What brand/model tires are on each and how many miles on each set of tires ?

Nitto Ridge Grappler 305/55R20 SL RATED
Toyo Open Country RT Trail 35X12.50R20 E RATED

 

[fordhouston]

Maybe the universe is just saying ditch the Ram and get another Ford

lol

 

[fordhouston]

38 PSI front and rear.

i'm currently running mine at about 39-40PSI cold. I'll probably drop it down to 35PSI or so and maybe that will help?

 

[TexasTruck]

maybe that will help?

For your Nittos… closer to the factory tires, 35 psi cold is OK. With the Texas heat coming we’ll gain 2-3 psi when they heat up. We know this… Tires can act as a “shock” absorber if you will. The stiffer the tire the less additional absorbency.

You lost me though, which tire are you running now?

 

[Calson]

I had a GM 2500 truck with E rated tires that took 80 PSI. When I first drove the F-150 with its passenger tires the ride was as smooth as for my Chevy Traverse SUV with its passenger AT tires.

Today there are "10-ply rated" tires that have fewer plies and are a bit of a fraud and more prone to sidewall failures and provide far less protection against rocks off the pavement.

With my 2500 class truck the tires were the primary limitation in terms of payload capacity and so I replaced the factory tires rated at 2695 with tires rated at 3750 lbs and gained a couple thousand pounds. I also added SuperSprings at the rear for a greater payload. On a 1500 class truck these upgrades would not provide the same benefits in terms of payload or handling. Better to just buy a F-350 or F-450 pickup instead.

 

[HammaMan]

There's many variables that go into tires including the wheel size. Sidewall flex is less on larger wheels. Running under inflated causes tires to heat up more as in rotation the contact patch area's side wall flexes much more causing heat and lower mileage.

Then there's the higher weight rated (E / LT) where the sidewalls are physically stronger providing better strength and puncture protection. This is true of the outer belts as well (aka tread belts). Not so much for some objects -- if they're big and sharp they're coming through. Rocks are an example where they can be pointy, but not exactly sharp like steel would be (not to say there aren't sharp rocks). There's better puncture protection in that realm too. Of course as mentioned there's tire brands which have different characteristics.

In towing, 18" LTs can feel like a 20" SL in terms of stability as the 18s have stiffer sidewalls, but the 20s have another inch of inflexible wheel present. The factory SL 20" have a load rating of 5360lb per axle. In short there isn't any magic variables that will tell you what's best for your use case. It's a given however that the stronger tire w/ higher pressure will result in reduced ride quality. You can also end up with additional noise and some tires it seems can never really be dialed in properly. They'll end up wearing poorly and can never seem to get a good lasting balance. That's typically present when there's a lot more rubber present.

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