Tire inflations real world?

So when I got my Tacoma the tires were inflated to 40psi cold. After a week a adjusted to the manufacturing door sticker of 29psi cold all the way around. I understand the come over inflated for shipping purposes from the plant but I was the first one to drive it off the truck so that’s fine. My question is two parts.

1. After my 1000k check up they inflated to 34psi cold all the way around. Why? Clearly above door recommendations. Am I missing something ? So this morning I’m planning on going back to 29psi unless other information arises from this thread.

2. Is there a standard for say a heavy payload or towing where an increase would be in order. Is there a equation. Like 2psi per every extra 1000lbs pounds?

 

Chalk test.

 

I think 35 psi is a universally know tire pressure that gives the best results maybe?

 

I don't do any towing, but I keep my tires at 32psi. 40psi rides a little rough. 32 seems fine to me.

 

It works as a starting point but really depends on too many variables to be universal. The chalk test accounts for everything in your particular set up and load. To be rigorous you should do it at various load levels so you know how much to put in or let out when the load changes significantly. Your tires will be on there for many thousands of miles so taking the time to learn what works best for you should be time well spent.

 

It depends on the tire. Does your truck have P-rated or LT tires? If your truck came with P-rated tires, the 29psi on the door jamb should be adequate to haul the max payload of your truck. If you were to upgrade to LT tires, it'd be a different story - they require more air to carry the same load.

 

We inflate high at the dealer so the tire light won't come on after a cold night. Toyota actually encourages this with their math for temperature changes.

The dead of winter is the only time I'll match the factory suggested pressure.

Tire lights scare customers, you wouldn't believe how much they freak out over one little light.

 

Google 'chalk test'.

Set your tires to door sticker pressure, cold.

Do the chalk test.

Adjust pressures as required to pass the chalk test well.

Note your proper operating pressure for that particular tire size brand, along with the conditions (loading) when test was passed.

Retest when loaded. May or may not need adjustments.

Use those 2 settings as needed.

When you get different tires, wheels, etc. repeat the process.

 

Well I live in Southern California so overnight temps aren’t an issue. If I do 29 cold they heat up to about 33-34 then back to 29 overnight. With no payload other than myself and MAYBE 150 lb in the bed with tools/materials. So my consern for door recommendations is to get the smoothest ride, best mpg and tire life. I firgured what’s on the door is what they engineered and I got “factory” tires
Firestone P265/65R17

 

Ha chalk test. Never heard of it. Sounds fool proof

 

It works as long as you don't exceed the load rating for the tires. At that point it takes more pressure than the tires are rated for to pass the chalk test. Below that you're gtg.