I just changed from the factory size 275-65-20 on 8" rims to 35 x 12.5 x 20 on 9" rims. I installed Toyo AT tires. At the shop they inflated them to 50 psi. The plackard states 65, but does that appply to all tire sizes or just OEM.

Thank you in advance.

 

I have my 35" wheels at 65. I believe that placard is for oem. You can look at your 35" for max press rating. I believe mine are rated for 80 psi max.

 

HI Caddy,

I did and I could swear it said 95, but now I am not sure. If I misread and it says 65 would you inflate to that or stay a bit below. I just think 50 is too soft.

 

Your tire pressure is relative. Say your factory tires can hold 2000lbs each at 100 psi. At Ford recommended psi of 65 you can hold 65% of the weight. If the new tires can hold 4000lbs at 100 psi you would only "need" to run them at 33psi to maintain the recommended weight carrying capacity.

This is just an example, please don't put your tire pressure at 33psi. Main point is see what the weight capacity of the new tires is and try to match it capability wise with the old ones and you should have no issues. I went up from 31.6" to 33s and run 5psi less per tire with good wear

Edit: also check the weight rating of the rims, sometimes people overlook the weight capacity of the rims and turn their 15k towing capacity into 5k because the rims aren't rated avenger near what the factory was

 

While I understand the correlation between capacity and pressure, I am merely asking how the size of the tires and their pressure relates to the OEM Pressure. When using factory rims I have always kept my tires are the factory recommended pressure even though I ran a larger size tire. This time I had a chance to buy rims and tires, look great, just not sure of the pressure and sometime you just can' t trust the tire dealer.

 

take a piece of chalk, and run a line across the tread from side to side.
drive around the block. look to see where the chalk is wore off. if it is only in the center, you have too much air int he tires. only on the outside too little air. completely wore even, proper tire pressure.

on my 02 diesel, i run 55 lbs front and 30 rear.

 

egg-xactly what I was going to post tjc...
do a search for the chalk test -
gives u the correct pressure for YOUR tires and YOUR truck and YOUR load...
to get the best contact patch and longest tire wear....

 

I run 45 in the front and 35 in the rear when not towing. When I hook the trailer up I run 60 allthe way around. I'm running 35x13.50-18.

 

I will do a search for the chalk test. I did increase them to 60 this morning. One quick question on the Chalk test. Drive in a straight line only or also turn. I would think turn will take it all off.

 

i make gentle turns.
a drive around the block for me is only around 1/4 mile.

 

With the entire tread on the pavement, traction will be better, especially with the crazy cold weather throughout the country.
Not a bad idea to lower more if necessary to keep the truck going straight right now.

 

I get good wear and performance at 65 psi on my aftermarket wheels and rubber. Like others said depends on how you load/drive your truck. And at 65 my tpms sensors still work.

 

Well here is what I have done over the past couple of days. Remember I am now sporting 20 x 9 rims with 35 x 12.5-20 Toyo Open Country.

I started with 50, seemed a bit soft.

I called Toyo, they recommended 65 psi, which is the max on the tire, based on the truck.

I filled them to 60. Today, perfect opportunity, dusty/damp road, I noticed that at 60 I have about 1/2" on each side of the tread, that does not get dirty, so I have reduced the pressure to 56 and I will updated tomorrow.

 

Its good to be diligent with the chalk test and tire wear. I have the fronts at 70 and the rears at 65 and have had even wear with that. I do adjust when towing and run 75 in the rears then. Even after the chalk test just monitor your wear closely. Ive got about 20k on my grapplers and theyre still running strong. Ive rotated often also as I like smoking them from time to time.