LT Tire Pressures

I just put on some LT295/70R18 KO2 tires and am trying to figure out what pressure to run. Based on the 4080lb axle rating I should be able to run 35 psi based onto the tire load charts which claim they are rated for 2295lbs @ 35 psi but some calculators say I need 40 psi? What's the offical source for proper loading vs pressure?

 

Take your original tire size and pressure and look it up on the inflation table to get the correct load capacity, cross reference your new tire size on the inflation table by size and load, and you can determine the correct new tire pressure.

The correct tire pressure recommended by the MFG is based on two things: the axle weight limit (but not HALF of it, as load is not always equally divided on both tires) and ride comfort. They recommend the minimum pressure to shoulder the load with the most comfortable ride. Handling is secondary, as long as the vehicle passes evasive maneuver testing, but if trailering and hauling, you may want more pressure in the tires even though they will shoulder the load without imploding at a lower pressure.

Anyways, if your door placard says 33 psi on a P275/65r18, the load table says 2502 lbs, derate by a factor of 1.10 = 2275 lbs (p rated tires must be de-rated when used on a light truck or SUV). Look up your new tire size and scroll over until you find a load rating equal or higher to 2275 lbs and look up at the inflation pressure. In the case of your lt295/70R18, 35 PSI shows a load capacity of 2295 lbs. [Edited for accuracy]

 

Thanks! This is exactly what I was looking for. So rerunning the math. Stock was 265/60R20 @ 35 psi. That's 2403lbs so derated that's 2186lbs. Using the LT295/70R18 @ 35 psi is 2295lbs which fits the bill and meets the axle loading with overhead. When I road trip it I'll run ~40-45psi for lower rolling resistance and better handling.