General rule for tire pressure?

acritzer wrote:
Thanks everyone.

I'm set now. Just second guessed myself after reading the bit online....the internet can always be a dangerous place to pick up info!

You are getting the same incorrect and potentially dangerous advice on this forum. Go directly to the tire manufacture's web site and get the facts. Some very good information can be found on the Michelin site, as well as Goodyear and BF Goodrich.

SHould have taken pics of my C2500 earlier today with 80lbs of pressure going into a topsoil yard. One could see the dust on the tire where it was hitting pavement. IE middle 8 of 9" of tread. Once I had the 4 yds of compost in the truck, you could see the dust from the yard on the WHOLE width of the tire.

I normally in this rig run the rears at around 50, 55 on the front when doing smaller loads and generally running around. Truck is around 5300-5500 empty with just me in it. My 3500 dually I sold 18 months ago, I ran that at 70 on the front, and 45-50 on the rears, unless putting a load of gravel etc for a length of time, then I ran them at 80. I had 90K on the Toyo M55's on the rear of that truck doing this. 80-90% of the time I ran at the 45-50 lbs.

While my way is not the chalk or tape method, still in the same vane, look at the tread after going thru a puddle onto dry road, the water wears off where contact is made, outside where not hitting will still be wet. Or dust as I saw. Or lack of dust.......

Marty

rhagfo wrote:

Cummins12V98 wrote:
I for one want my trailer tires to grab the road as much as possible in hard braking and not skid as they could with overinflation for the LOAD.

So Cummins how do you get around the TPMS alert, or do you just ignore when running empty?
I don't need to deal wit a TPMS, so not an issue for me to run the correct pressure for the load.

All you have to do is step up to a manly man's truck and get the 3500HD DRW. Shows pressures and no alerts!

Cummins12V98 wrote:
I for one want my trailer tires to grab the road as much as possible in hard braking and not skid as they could with overinflation for the LOAD.

Exactly, even trailer tires need proper traction.

I will say that I always used inflation tables on my ST's and never has an issue. If I was going on a long higher speed trip I would add 10 psi above chart and still have plenty of braking and cool tires.

All of my ST flats were rock punctures in places most don't take TT's, and the punctures are the main reason I now have LT tires on my TT.

My camper trailer is tandem axle, with load range D Kumho 857 radial tires. The actual load on the tires is 3500 pounds. The rated load capacity of the sum of the four tires is 7496 pounds, meaning I am running at only 47% of the rated weight load.

In theory, since I run 65 psi ( max sidewall pressure ) I should be seeing a wear pattern that would indicate "overinflation". That is not the case however. I now have almost 15K miles on them, and all four tires are wearing perfectly even ( they have used approx 2/32" tread from new ).

I can't address whether the truck and trailer would stop shorter, longer or the same with different inflation pressure, because I have not tested it, nor do I have a good way to do so. I do know the brakes on this trailer are capable of locking the tires, because I have to use less than maximum setting on the prodigy brake controller.

To the original question of this thread, for one of my trucks ( the Nissan ), pulling the little camper, the door sticker says 35 psi. I run 35 in the front, and 38 in the rear when towing.

On the other truck ( F350 dually ) I run door sticker pressure ( 75 front, 60 rear, and these are LR E tires, 80 psi max on the sidewall ) all the time, towing or not.
On all my trailers, I run max sidewall pressure, which is 65 for the LR D tires and 80 for the LR E tires.

There is an exception here. I once bought a large trailer to tow behind an Expedition 4x4 EL (already a heavy vehicle). I could tell tires even inflated to the max were not right and got lots of sway. I bought new tires for the SUV (same size) but higher load range. The max pressure was something like 100 psi, the specs on the door were something around 40 psi. At max pressure these tires rode like they were solid steel even pulling an 8k lb trailer, so I played with the pressure a little. If memory serves me (about 5 yrs back) I used 80 on the rear for towing and 60 on the front. When not towing, I think I used 50 on all. I am sure there is a scientific way to get this right, but I will say when not towing, and lowering the psi to 50. I got a decent ride and the SUV handled far better in turns etc. btw, the TPMS will not work with higher range tires as it always senses tire is over inflated, Ford would not reset for me. So, I just manually checked tires often. I will say for anyone towing a heavy trailer, check out if you can get a higher load range tire for you tow vehicle. It makes a huge positive difference.

Cummins12V98 wrote:
I for one want my trailer tires to grab the road as much as possible in hard braking and not skid as they could with overinflation for the LOAD.

So Cummins how do you get around the TPMS alert, or do you just ignore when running empty?
I don't need to deal wit a TPMS, so not an issue for me to run the correct pressure for the load.

You will find most new pickups door sticker stating the max of 80 psi for rear tires. And the tpms setting a light off at 20 percent less than that. It's new fed rules.

I for one want my trailer tires to grab the road as much as possible in hard braking and not skid as they could with overinflation for the LOAD.

Whether it's "correctly" inflated or run at sidewall maximum, you'll probably still scrub more rubber off the tread backing into the camping space than you did on the drive to the campground. Every turn you make is going to spread the wear evenly across the tread as well. The straight ahead rolling down the highway miles may not make a whole lot of difference in the overall tread wear pattern of a RV trailer tire.

That's why I think the "inflate to maximum" and the "inflate by load chart" sides can both be right on this issue. It just doesn't matter that much.