tire pressure question
Just put Michelen lt tires on my 2013 f150 4x4 cc. Max pressure is 80 psi. E rated. My question is what would be a good pressure to run when not towing or hauling? What do you folks do? Door jam...
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They did do a look up and said to get the same max load capacity as my original P tires I would need to inflate to 55psi.
Yeah Tireman9 one of our resident tire engineer has brought this to our attention before or you can find it on his rvtiresafety.com website.
And this posted before from Capriracer (Barry Smith) tells us why the LT E needs 50-55 psi to get the same load capacity:
*** CapriRacer LT requires 15 psi increase above P tire pressure
Perhaps I should have approached this from a different angle - and I'll do that after I clear up an issue.
The maximum pressure is not the same as where the load carrying capacity maxes out. On P metric Standard Load tires, the load carrying capacity increases as the inflation pressure increases - up to 35 psi.
The maximum usage pressure for a Standard Load P metric tire might not be 35 psi - it might be 44 or 51 psi, but that doesn't change the relationship between the pressure and the load.
Don't believe me? Find a load table for P metric Standard Load tires and see for yourself. They all end at 35 psi.
OK, here's the different tack on the issue at hand: Increased inflation pressure when going from P metric to LT metric tires.
On every vehicle sold in the US, there is a sticker, called the vehicle tire placard, that lists the originasl tire size and the vehicle manufacturer's Inflation pressure specification. For pickup trucks using P metric tires, no vehicle uses more than 35 psi for the specification (which is in line with where the load carrying capacity maxes out for P metric tires).
If you do the math, you will find that the load carrying capacity of P metric tires is the same as the same "size" LT metric tire +15 psi.
Don't believe me? Get the load tables and do the math yourself. (Don't forget to derate the P metric tire by a factor of 1.1 because it is being used on a truck!)***
The OP already has his tires but a better tire choice for replacing a P on a truck is a LT load C or D tire. However for some reason there isn't many C or D tires available especially 18" and 20" sizes. Big tires on a 1/2 ton truck sometimes are a handicap.
