tire pressure
Thread Starter
Formerly "ZCHPRO"
Joined: Jul 2010
Posts: 1,950
Likes: 36
From: Chandler
tire pressure
Hey guys I'm no longer running the factor 275-65-18s or whatever the LT package has and I'm now running 265-70-18s I was wondering what the cold psi rating was for our trucks with this kind of tire? anyone know? do any of these trucks run these tires on stock?
Thread Starter
Formerly "ZCHPRO"
Joined: Jul 2010
Posts: 1,950
Likes: 36
From: Chandler
Really? I've heard that its just what the tire co. says to avoid a lawsuit but you should go according to the cold psi rating on the door jamb (I don't have a rating for this tire)
Senior Member
Joined: Sep 2009
Posts: 1,073
Likes: 28
From: Phoenix, Arizona
If no better solution comes along I would think that 40PSI would be safe. You could use the max pressure on the tire itself but I would think that the ride would be hard. Of course if you are hauling a big load in the bed the max pressure would be very beneficial.
Ford F150 FX`
Joined: Sep 2010
Posts: 1
Likes: 0
From: NW Iowa
My brother in-law has been in the tire business for over thirtyfive yrs.
He says the sidewall will tell you what the maximum psi for that tire.
When you haul a large load go with that. They want you to have the same footprint
as you would when you have normal loads. The door will tell you what to have
under normal loads and have the best ride and footprint for wear.
He says the sidewall will tell you what the maximum psi for that tire.
When you haul a large load go with that. They want you to have the same footprint
as you would when you have normal loads. The door will tell you what to have
under normal loads and have the best ride and footprint for wear.
Last edited by Ford f150 fx; Oct 7, 2010 at 03:17 PM.
DIY
Joined: Sep 2010
Posts: 1,325
Likes: 11
From: South Florida and NYC part time
from somewhere else:
The right illustration is a cross section giving a better view to what proper or improper inflation does.
Under-inflated: Wears the edges of the tread more than the center.
Over-inflated: Wears the center of the tread more than the edges.
Proper: The entire tread is worn at the same rate (aka, correct pressure).
Chalk Line 
Over Inflated 
Proper Inflation
The right illustration is a cross section giving a better view to what proper or improper inflation does.
Under-inflated: Wears the edges of the tread more than the center.
Over-inflated: Wears the center of the tread more than the edges.
Proper: The entire tread is worn at the same rate (aka, correct pressure).
What to do?
Checking proper tire inflation is rather simple and requires some chalk or a utility crayon.
Make a mark all the way across each tire.
Drive the Truck for a short distance, a straight line is best.
Note the wear pattern in the chalk. If there is chalk left at the edge the tire is over inflated. Chalk left in the center means it's under-inflated. A clean pattern indicates the pressure is just right. Make a note of the pressure for future reference. This procedure would need to be performed again of different size or style tires are added.
Chalk Line
Over Inflated
Proper Inflation
Last edited by picaflor; Oct 7, 2010 at 03:45 PM.
Fords For Life
Joined: Jan 2009
Posts: 1,086
Likes: 14
From: Manhattan, KS
go with the door jamb not the sidewall. As many have said that is the max for the tire but not exactly the best pressure. Stick with the door jamb for normal operations I think it is 35 PSI.