I was wondering if anyone could give a recomendation on the correct PSi to run on 35/12.5/20 Nitto Trail Grapplers. I want the best ride and MPGs. They are E rated and the max PSI is 65. With the 1500 being light what would you recommend. I have them down to 40psi now. Thanks

 

What are the stock 20's supposed to be at, 35? I'd go w/ 35-40, so I think you're good.

 

For best ride and MPG run the max PSI that is recommended. Running a lower PSI will cause the tire to deform more while driving. This does two major things. First it increases your rolling resistance of the tire. While you do get a larger contact patch with the road, your engine must do more work to overcome this extra resistance (i.e. lower MPGs). Secondly it decreases the responsiveness of the tire. With a lower PSI the tire wraps more under acceleration and the sidewall is less able to resist lateral loads. This will cause your handling to suffer. Really the only time you should run less than max pressure is when you are driving through soft surfaces like sand.

Also as a side note, unless you are running bead locks or bags, an underpressurized tire is more susceptible to being knocked off its bead (such as if you were offroading, or side swipe a curb).

(And i know there are many of you who will correct me and say it also affects tire wear, tire heat build up, etc, but I was just hitting the key points rain asked for.)

 

always use the tires recommended pressure rating and not what the truck says. Dodge does not make the tires.

 

The problem with that is the tires say max 65psi and tires this size are not made for a 1/2 ton. Thanks for the input though....I appreciate it.

 

max pressure is for max load it is not the recommened pressure,max pressure will give you the best mpg but your truck will ride like a dump truck and be riding on the center tread over inflation is bad too.you should be in the 35-45 psi range depending on options,load,etc...

 

Exactly. If you run them at 65 psi, plan on replacing them in a short amount of time from the centers wearing out.

35 psi is what I would run. You could try 40 but keep an eye on the little nubs on your tires. If the center ones disappear first, then you are running too much pressure. I would bet that that would be too much for the rear without any load though.

 

I run mine at 46psi

 

i would run 35 all the way around. 40 would be a little too much and would defentally wear the rears out way too quick. just my .02 cents from working at a tire shop. and btw your truck looks really good.

 

Wrong. Running them at the max pressure will not wear out the center of the tire or hurt anything. if that were true then you would see a lot of trucks with the center tread worn out. I have always run my tires within 2 to 3 psi of the max and have never had that problem. Plus my dad has a 3/4 ton ford that we run the max pressure for the tires and his always wear evenly across the tire.