What tire pressure to run?

I recently had my 275/70R17 KO2's installed about a month ago. I'm not 100% sure what Costco inflated them to but I'm guessing 35 PSI. I noticed this morning they looked a little flat (can't remember if it's always been the case or went a little lower since installing) but I was getting horrible gas mileage and could definitely notice the drop from stock. This morning I filled them up to 42 PSI because with Hawaii heat I'm thinking they'll go to 42~45. Instantly they feel so much better on the road and filled up the tank right after so we'll see how it affects gas mileage.

 

Hey, sorry to ask on such an old thread, I have Falken Wildpeak AT3s and it is a 116T load index and an SL load range... Is that P or LT? Or something else?

 

Something else...
ERTRO-metric; euro-metric

 

door jam

 

I'm not sure what that is but it gives me something to look into, thank you!

The door jamb lists the pressure for the stock tires, I have different type and size on

 

SL is standard load, same as P or Passenger car tires.


The number on the door jamb is for best ride with P, or SL rated tires with an empty truck. There is a number stamped on the tire as well. If you're hauling any weight in the truck, or towing a trailer which adds weight to the truck you need to be closer to the number on the tire rather than the number on the door jamb.

It varies somewhat but the number on the tire is somewhere around 44 PSI. When I had P rated tires I ran 36-38 PSI all the time. I hauled loads frequently and it was just easier to keep enough air in the tires all the time than to have to add air every time I hauled something. I got about 1 mpg better fuel mileage at that PSI too. Tires lasted just as long.

If you move up to E rated tires none of the printed data for PSI means anything. The C and D rated tires are close enough to P rated tires, but E's are a much tougher tire. You actually need LESS PSI in an E rated tire to carry the same weight you'd carry with P or SL tires.

E rated tires are designed for heavy duty trucks with 7000 lb curb weights and GVWR exceeding 10,000 lbs. A Tacoma's GVWR is under 5500 lbs, curb weight just over 4000. On heavier trucks E rated tires are typically inflated to 60 PSI unloaded and as much as 85PSI for heavy loads. With a Tacoma rated for 1/2 that weight, about 1/2 that PSI is a good place to start. I now keep 30-32 PSI in my Tacoma and can't imagine ever needing more than 40 PSI to haul anything. But you just have to experiment if you go to E rated tires.

 

Awesome, thank you! My shitty gauge told me 40PSI all around, so I will drop to 35ish, and pick up some chalk later. I really appreciate the explanation!

 

Tire only shows max pressure. Not what to run.

 

door jam lists the PSI on the unloaded weight of the truck not the tire size

 

It definitely has tire size and while not horribly clear, the grid make it looks like the PSI applies to that tire size

 

Here's a handy pressure calculator that lets you adjust for whatever new tires:

 

I’ve noticed that if the psi is low 30s for the 265 70 16s, the ride on pavement with cracks is more ruff than higher psi. Other way around when off roading

 

Any tire pressure recommendations for Falken Wildpeak AT3W 315/70R17 10 ply (E load)?

Tire shop put 35 psi which is so stiff I can feel the paint lines in the road. Aired down to 25 psi but chalk test still shows about an inch of tread not contacting the ground in the rear. I think this is because most the weight of the truck is in the front and I currently have nothing in the bed, just a tonneau cover and gas tank skid plate.

 

Biggest problem is, that tire is very voluminous; it doesn't take a whole lot of psi to achieve the necessary load capacity.
@ 35 psi, it has a load capacity of 2,535 lbs; it only requires an inflation psi to achieve 1,954 lbs. Charts don't go below 35 for LT tires. Chalk, unfortunately, is your best bet.

Just for comparisons sake; an LT 265/75/16 achieves 1,948 lbs @ 36 psi and 2,532 lbs @ 52 psi