Increased tire size, same psi?

I was. He has a '17 Offroad

 

Depends more on the load rating, stiffer sidewall requires less pressure. I currently run 28 PSI in my 285/75/17’s and I honestly need to lower the pressure in the rear.

 

Lol...
You entered P265/70/16.
Try again; P265/65/17/ @ 29 psi

 

Again, I took the size from your post.

 

I'm the confused one now; I'm getting posts mixed up.
We're talking about @Lt. Dangle...

You should be entering a euro-metric 265/70/16/112 @ 30 psi

 

Which I did and you said I should have used 29

Post #29, ironically

Either way, I was just showing a resource for a good starting point. No need to argue. I probably put the wrong info in again anyway.

 

Guys @splitbolt @Thatbassguy , I'm just gonna go to 36 cold and it probably will warm up to 40 PSI or so and call it good.

Thanks for the clarification. I knew what you guys meant and it was helpful. Thanks. I'm just happy I don't have to go to 45 PSI lol.

 

Use the calculator.

Don't trust me or anyone else to put the right numbers in.

 

Don't worry...it's just friendly banter.

 

I don't even trust myself at this point.

Honestly, I go by feel anyways lol. I just wondered what was the "proper" PSI. Now I know. Or think I do anyways, and that's all that matters.

 

Just ran it on the calculator provided and confirmed that the PSI I've been running ( 27 psi) for the last 2500 miles is correct.

I believe I used this link provided a few months ago to get that 27psi pressure.

Viewed the manufacture specs for the OEM tire and the larger tire I installed to validate the load ratings.

 

I don't see where I said 29 psi in post #29 or post #27, the one you quoted.

In fact, I tell Lt.Dangle 36 psi in post #27.

 

@Thatbassguy

This calculator doesn't 'round up'.
You're supposed to inflate to or above the target weight of 1,954.

Close enough; agreed?

 

See above

Which was still wrong based on the information I got from post# 27

 

Wasn't trying to argue. I wouldn't know what Tacomas come with what tires and recommended inflation. I just put in the information I got from your post. You had circled the load rating in the 30 PSI column, so I put that in. Then, you said I should have used 29 PSI, so I did.

 

Just friendly banter to clarify things...
As I said, I got OP confused with Lt.Dangle.

In post#29, you entered a P-metric P265/70/16 @ 30 psi.
It should have been euro-metric 265/70/16 @ 30 psi.

You will get the same result if you input a euro-metric 265/70/16(Offroad) @ 30 psi or P-metric P265/65/17(Sport) @ 29 psi; and output an LT255/80/17.

 

I should have read more carefully. I didn't think there would be a difference between P-metric and euro-metric. I guess I learned something today.

Some of this tire math is over my head. I've always wondered (or, for the last few years at least) why the LT tires require more pressure to carry the same load as a P-metric. I realize there's some science behind it. I would love for a tire manufacturer to dumb it down for me so I could really understand it.

 

Two balloons of equal size, but one is thicker than the other. Which requires more pressure to inflate to equal size?

 

I guess that makes sense. But, tires don't increase in size when inflated.

 

With the vehicles weight on the tires, starting from say, 5 psi and inflating to 30 psi; the tire volume does not change?

It has a bit to due with deflection and heat as well. LTs being stiffer, require more pressure to attain comparable deflection.