LT air pressures

[CapriRacer]

Is that C D or E?

Load Range C

Chalk test - Run a thick chalk line across the entire tread. If you have too much psi in the tires, it will only wear the center and leave the chalk on the edges. You are wanting the line to wear off evenly across the tires available tread.

The chalk test is unreliable. It assumes that the contact patch will be optimal when the pressure is proper - and that is not always true. Consider:

That footprint is going to result in a lower pressure - one that risks a load related tire failure.

 

[burbguy82]

You know i don't know where he came up the PSI setting. I guess someone at the dealership told him that.
My 99 Suburban came with LT tires and the sticker on the door said 65 lbs. I should was glad to get rid of those tires. Why would anyone pout LT tires on a 1/2 ton truck ? Maybe if it was down on the farm all the time i could see it.

I think you are misunderstanding LT and load range. They are not the same thing.

PSI has to do with load

LT stands for light truck, which a 1\2 ton is, and 3\4 and 1 ton trucks btw.

 

[snarl]

https://www.tirerack.com/upgrade-garage/what-are-load-ranges-ply-ratings

https://www.tirerack.com/upgrade-garage/what-is-load-index

 

[hardheaded]

I called my son and these tires are **** Cepek trail country LT285/65/18
They ride like they are square with 45 lbs. in them. Don't know what came on the truck when new.

Found the max pressure 80#, looking at some other web sites it looks like he could run down to 35. Maybe try 40 for awhile and see how it rides.

 

[CapriRacer]

I called my son and these tires are **** Cepek trail country LT285/65/18
They ride like they are square with 45 lbs. in them. Don't know what came on the truck when new.

Found the max pressure 80#, looking at some other web sites it looks like he could run down to 35. Maybe try 40 for awhile and see how it rides.

At this point, we need to know what the vehicle tire placard says for tire size and inflation pressure. It might be that those 285's are 2 sizes larger than the OE size, which means you can get the same load carrying capacity at a lower pressure = no safety risk.

 

[Rand]

They are also apparently load range E tires.

At this point, we need to know what the vehicle tire placard says for tire size and inflation pressure. It might be that those 285's are 2 sizes larger than the OE size, which means you can get the same load carrying capacity at a lower pressure = no safety risk.

They are also apparently load range E tires.. so are clearly aftermarket.. we dont know the OE Tire specs at this time.
If the 18" wheels are stock that seems to indicate it came with P-metric at least according to normal internet sources such as tirerack.

until @hardheaded posts a door sticker we will remain in lack of information limbo.

 

[hardheaded]

truck came with P 265/65/18 rated tires at 35# of air. Just a standard 1/2 ton Z71 4x4 crew cab.

 

[CapriRacer]

truck came with P 265/65/18 rated tires at 35# of air. Just a standard 1/2 ton Z71 4x4 crew cab.

OK, the pressure can safely be dropped to 40 psi.

 

[LouC]

There were some charts floating around the internet that listed how much you have to increase inflation pressure if you use LT tires on a vehicle that came with P rated tires. We did this on our 98 Grand Cherokee & went from 36 to 42 psi. 30x9.5-15 LT tires.
Another related issue is trailer tires. Most people have no idea what their trailers weigh when loaded but if you get it weighed you might be in for a surprise. I upgraded mine from load range C tires to load range E tires (80 psi) the biggest (225/75-15 ST) you can put on a 15” trailer rim. Trailer manufacturers used to spec very little reserve capacity in their tire/wheel/spring/axle choices, like 10% vs vehicles which usually have 20-25% reserve capacity. When I redid my trailer I used a 6,000 lb axle with 3,000 lb hubs & brakes. The most you can get on 15” rims is 2830 lbs per wheel with load range E tires @ 80 psi.