PSI help

hey guys im confused. what psi should i be running on my taco? my tires are 285/70/17. the psi on these are 65. on my stock tires (265/75/16) i believe it was 32 psi. i took it to goodyear for an alignment and they set it to "65 psi" then when i took it to Toyota for the recall i think they set it back down to 32 psi? i think just cuz they look lower. whats the correct psi i should run?

 

65psi? Are you running light truck tires? If you aren't and they set it that high avoid that place like the mall before Christmas. Even if you are running LTs that's way too high for the load those tires are under. I'd use the stock pressure for now. Keep the tires inflated and monitor how they're wearing. If you see the middle wearing faster than the edges up the pressure a few pounds. If you see the edges wearing faster drop a few pounds. I personally think it'll be one or two pounds less than stock but I don't have any experience to correlate with thus the stock pressure recommendation.

If you want to be super accurate ask the manufacturer of the stock tire and your aftermarket unit for a psi to load chart. Take the loading per tire stock and apply to the aftermarket tires and that should give you the correct pressure.

 

Im pretty sure recommended PSI is also stated on the tires.... Sorry if Im wrong

 

Tire psi is also rated by the vehicle they are being put. Every vehicle has a different curb weight. I believe the max psi is printed on the tire. What did was call bf Goodrich, and they had a menu option for proper tire inflation for size of tire and vehicle. You will need stock tire size, and psi. Plus your new tire size

 

go with the vehicles' psi. whatever it says on the door frame. never exceed max tire psi. youl never have to worry about that in th tacoma though.

 

Chalk test

 

That's only accurate for the OEM tires

 

But if you change tire size, stock psi is no longer accurate. Aside from calling the manufacturer, I agree chalk test would be the next best choice

 

its always worked for me, but yeah doing some sort of mark test would work well too.

 

pardon my noobness but, what's a chalk test?

 

Basically , you take blackboard chalk and draw a line across the tread patch of your tire , side to side .

Drive a bit , and check the chalkline .

Wearing evenly shows a good inflation .

Wearing in the middle and not the edges points to overinflation .

Wearing at edges points to underinflation .

 

The number on the tire is the max pressure, the maximum it can sustain indefinitely without bursting. This is NOT the correct pressure for the tire's load as the tire manufacturer only knows what range of loads the tire should be put under. The vehicle manufacturer knows the typical loads each axle will be under and with data from the tire manufacturer sets the stock pressures accordingly.

In reality it can take a bit more than max, safety factor and all, but passenger tires (which these trucks all come with stock) are usually only good for about 44psi so at 65 I'd be very concerned driving with them fully loaded. Light trucks are usually rated for 80psi max and semi tires are even higher, around 125 I believe.

 

check this link out...
http://www.nitrogentiremachine.com/proper_tire_inflation.htm

 

excellent 411. thanks guys.

 

All depends on what your purpose is, and what tires you have mounted.
First, go by the tires. Never exceed the maximum pressure listed on the sidewall. Now that you have your upper limit......
Hauling lots of weight? High pressure, near or at the tire's maximum.
Driving offroad? Generally going to be low pressure. But keep in mind that terrain varies so much that pressures will to. For example...
Driving in sand? Going to be extra low pressure (in the low teens).
Want a soft, smooth ride? Use the manufacturer's recommended pressure, or a little less.
Want to maximize fuel economy? Run slightly higher pressures. (This is where I usually aim. I have 44psi tires, and I run 42psi when on road, variable but low when off road. My last truck I ran 44psi on road, despite the tires being 65psi tires. With 35psi tires, I would suggest 33psi on road. So long as the tire is listed at or above 44psi, I would generally recommend about 42-44psi for maximum fuel economy with even tire wear and decent ride.)
Always keep an eye on tire wear (a chalk test is good for instant wear reading), and adjust accordingly. Early wear in the center = too high a pressure. Early even wear on the edges = too low a pressure. Early uneven wear on the edges = alignment issues, or lack of rotation.
Play around with the pressures and find what works best for you. Note the ride quality, tire wear (chalk test this), fuel economy, and traction. Stick with what works best for you.
And always keep it below the maximum.
One more important note: all pressures listed on the tire, the door frame, and in this post are assuming cold tires. That would be tires that have been driven less than one mile, and have been sitting in the shade. Assume about a 3-5psi increase in gauge pressure when checking hot, and adjust calculations accordingly.