PSI debate from metric tire to LT tire.

[Pelo18]

Fellow, 6G4R members,

Have a question about the PSI for a LT tire? Door jamb says "33 PSI" for tire. But, based on information from tire pressure calculator it recommends "45 PSI" for mine LT265/70R18 E load tires. So, can someone shed some light on this. I'm hearing about the chalk test as well.
Thanks, in advance.

https://tiresize.com/pressure-calculator/

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[MikeD]

I use the same site which has my 285/75R18 E-load at 36 PSI: Tiresize.com pressure calculator
I was surprised by your PSI number so I had to check but, yep, that is what it says for your E-load 265/70s:

OEM Size (P265/70R18 SL) Load Capacity: 2542 lbs. @ 33 psi.

Passenger type tires are fitted with a 10% overage in load capability when used on SUV's, Light Trucks, and Vans because of the difference in load handling. This load overage can be removed when changing to an LT type tire.

That brings the effective load capacity to acheive down to 2311 lbs.​

New Size (LT265/70R18 E) Load Capacity: 2340 lbs. @ 45 psi.​

**Assessing tire contact patch for proper treadwear is always recommended.​

Only explanation is that is what it takes to maintain the comparable load rating. The E-load tires are rated up to 80 PSI so I guess its a design factor to provide appropriate stiffness. If you are towing a heavy load you might even want to go higher. OTOH if you are running empty you could certainly get away with dropping that 45 down a few pounds. Likely still will be a bit stiff. The joys of E-load. (Mine felt great off-road yesterday at 19#:>)

 

[Joestac]

I swapped to 275/70/18 Toyo AT3 E loads on Saturday and I've been running 33 still. I'll do a chalk test and see how it is looking. Without a heavy load the tires seem to squat the same as the SL tires that came on the vehicle at the same PSI. Like Mike said, if I was loaded up I'd definitely add some more air.

 

[CO/ZA]

I have LT275/70-18 E loads and went up to 37psi.

Seems fine, wear is good - still doing 19.8mpg.

 

[xp0nex]

I have C loads and went with 34. Wear is good and plenty stiff.

 

[mcd_ovrlnd]

My installer set my 265/70 R18 Load D KO3s at 40.

 

[Joestac]

I swapped mine to 38 last night from the 33 they were at. Felt pretty good this morning on the way in. Little bumps in the road were felt slightly more but nothing terrible. Should offer better rolling resistance as well for slightly better MPG. Time will tell. Still need to grab some chalk to do a test in the garage.

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