SL tires @ 51 psi vs XL tires

[Mosey]

I have been under the impression that SL rated tires with 51 psi max pressure were basically the same as XL rated tires. Both are 4 ply and have max psi of 51. Weights appear to in the high 30 to mid 40 lbs for 275/65r18. Load ratings are similar too.

So, is there really a difference?

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[Samson16]

PSI is a good indication, but I found this:

LOAD INDEX AND LOAD CARRYING CAPACITY
Load index is another way to further describe a tire’s carrying capacity. The load index explicitly indicates the max load a tire can carry. To find your tire’s carrying capacity, look for the load index number on the sidewall. Load index is a more precise method of measurement than load range which focuses mostly on construction.

For example my OEM Dynapro AT2 tires have a load index of 115 which equates to #2679 carrying capacity per tire.

The same sized KO2 has a load index of 119 or #2998.

I'm quietly searching for that magical combination of weight, durability, load carrying, and ride quality my Unicorn truck deserves lol.

 

[Mosey]

Here are three examples, all with a load index of 116.

https://www.discounttire.com/buy-tires/yokohama-geolandar-a-t-g015/p/27679

SL 116 51 psi

https://www.discounttire.com/buy-tires/yokohama-geolandar-x-at/p/146167

XL 116 51 psi

https://www.discounttire.com/buy-tires/continental-terrain-contact-a-t/p/32274

SL 116 44 psi

 

[Samson16]

From Discount Tire:

Looks like the SL/XL is just marketing at this point. Those tires left the SL range at 42psi.

 

[Mosey]

Thanks. Good info.

 

[HammaMan]

I'm convinced the tires that come on the F150 are products made for ford with ford's specs. At 51 psi they're XL tires on specs alone. While it would be false advertising to rate an SL tire XL, it's not when selling an XL tire as SL. The pressure specs don't lie. Ford doesn't want a repeat of the firestone exploder debacle again so the factory tires are SL labeled XLs to cover ford's ass and NOT lock buyers into being suckered into XL tires on replacement.

That's my theory and I'm sticking to it. Match tires to your needs and don't worry about the SL/XL labels unless you're placing unusual burden on them.

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