Everything I read says tires should be inflated to Max psi. Is there general agreement on that? I plan to do whatever is safest and as of last evening, my tires are at 60 and Max is 80, so I have some filling to do.

rvshrinker wrote:Everything I read says tires should be inflated to Max psi. Is there general agreement on that?General agreement, yes - total agreement, no. ;) Forum pundits who will claim to be experts on the subject would insist you load the trailer as it would normally be for a camping trip, take it to a weigh station, and measure not just the gross weight of the trailer but also the weight bearing down on each side of the trailer, then adjust your tire inflation to match. The reality is almost no one does this, simply inflating to the maximum imprinted on the tires' sidewall.

rvshrinker wrote:Everything I read says tires should be inflated to Max psi. Is there general agreement on that? I plan to do whatever is safest and as of last evening, my tires are at 60 and Max is 80, so I have some filling to do.I called my tire dealer (Les Schwab) with the same question. The general agreement is to fill the tires to the max. capacity of your tire. To run your tires at 60 psi could lead to tire damage/blow outs/damage to your trailer and accidents. When I am not towing my 5th wheel trailer I run my tires at about 60 to 65 to make the ride more comfortable.

To be clear, I'm asking about the trailer tires. I keep my 2017 SRW 3500 in the sixties when empty, at 80 when towing.

For ST tires running them at or very close to max psi supposedly increases their ability to perform as designed, inflated to low causes them to heat up which eventually leads to bubbles and tread separation. We always run our ST tires very near to or at max psi and have had no blowouts or even a flat over the last dozen years, although we dutifully replace our ST tires after 4 years of use. LT tires are typically filled to a psi that matches the load they are carrying, we keep our LT tires filled to the psi stated on the door placard of our Silverado HD truck.

You will get two answers. As you stated max psi stated on the tire or the trailer placard which is more then likely max psi on the tire sidewall for the oem tires. The other answer is weigh the rig and set the psi per the tire manufacturers load inflation table for that tire. which may or may not be the max psi on the tire sidewall that will depend on the weight they are carrying.Personally (and I have upgraded the tires on my trailer to a higher load rated tire than came oem) I go by the load inflation tables based on the weight of the axles and I add extra for an additional safety margin. My trailer came with Ranier 225/75/16 load range d tires with a max load of 2540 at 65psi, my new tires well at the time new were load range e with a max load of 3420. Even at 65 psi (same psi as the max on the oem tires and trailer placard) have a load rating of 3000lbs substantially higher load at the same psi rating. My trailer axles weigh in around 7900lbs for both axles for how I load the trailer so for easy rounding lets say 2000lbs per tire and according to Goodyear's table I can run that at 35psi for a load of 2020lbs. Which is not enough margin for me so I run them at 55 to 60psi which is 2730-2870 worth of load well above the oem tires load of 2540 at 65psi. I get a better ride at the lower psi and still a larger load margin so win win for me in my mind. I am sure someone will tell me I'm an idiot for not running the max 80psi on my (new) tires. However I trust the tire manufacturers knowledge of their tires much more than the trailer manufacturer who does not make or engineer tires.

Correct inflation of trailer tires | Good Sam Community

TravelinDog
Explorer II
Aug 06, 2019
Grit dog wrote:
sgfrye wrote:
drsteve wrote:
Inflate to max inflation as shown on the sidewall.

x2
no need to overthink it. has worked for me. autos, boat trailer tires, and motorcycles

Fwiw, that’s actually under thinking it by a good margin.

Some people just like to overthink and complicate everything.:h
Planning
Explorer
Jul 31, 2019
Per Goodyear:

"...it is recommended that trailer tires be inflated to the pressure indicated on the sidewall of the tire. Trailer tires experience significant lateral (side-to-side) loads due to vehicle sway from uneven roads or passing vehicles. Using the inflation pressure engraved on the sidewall will provide optimum load carrying capacity and minimize heat build-up."

Reams of information here by a tire engineer supporting sidewall cold inflation pressure as being optimum to reduce interply shear.

http://www.rvtiresafety.net/search/label/Interply%20Shear

With tires on multi-axle trailers, like RV trailers, the belt (interply) shear forces can be 24% higher than the belt shear forces of identical size, load and inflation tires on a motorized vehicle.

The internal structural forces are different for torque than for high "slip angle" which is the situation in trailer application. Front tires on cars, motorhome or tow vehicles experience slip angle usually in the 1° range while trailer tires are subject to angles in the 10° and greater range. The forces are NOT linear. 10° can generate significantly more shear than 1°.
Optimistic_Para
Explorer
Jul 30, 2019
drsteve wrote:
I am talking only about tires on a towable.

I know. That was directed towards the OTHER guy, who apparently runs his CAR tires at max inflation . . .
BillyBob_Jim
Explorer
Jul 30, 2019
pitch wrote:

Some of you guys could suck the fun out of an Ice Cream Social!

That's a good one LOL. :B
Grit_dog
Navigator
Jul 30, 2019
sgfrye wrote:
drsteve wrote:
Inflate to max inflation as shown on the sidewall.

x2
no need to overthink it. has worked for me. autos, boat trailer tires, and motorcycles

Fwiw, that’s actually under thinking it by a good margin.
pitch
Explorer II
Jul 30, 2019
Inflate your ST's to max to get maximum use.
Who the hell weighs each side? What do you do adjust your inflation because the gallon of milk you drank has changed the formula?
Why do some have to make everything an exercise in engineering? Now if you have 7 anvils over the left side maybe you should look at lateral scaling,other than that, eh maybe not all that important.

OMG we are down to less than half fresh water, pull over and adjust the inflation before we burst into flames and die!

Some of you guys could suck the fun out of an Ice Cream Social!
drsteve
Explorer
Jul 30, 2019
Optimistic Paranoid wrote:
sgfrye wrote:
drsteve wrote:
Inflate to max inflation as shown on the sidewall.

x2
no need to overthink it. has worked for me. autos, boat trailer tires, and motorcycles

As far as cars, vans, pickups, and motorized RVs go, inflate your tires to maximum and go to a mall before it opens. Use a piece of chalk to put a line across each tire, and drive a couple of hundred yards. Then check your tires. In most cases - depending of course on your vehicle weight - I think you will see that the chalk is worn off in the center, but not at the edges, which indicates that not all of the tire tread is making contact with the road.

It seems self-evident to me that this is NOT optimum for either steering traction or braking in the shortest distance. And I suspect you will also be more prone to hydroplaning in the wet than if your tires were making complete contact with the road.

Both Goodyear and Michelin have downloadable RV tire publications, available here:

Recreational Tire Care Guide

RV Tire Guide

They both warn against overinflating tires because of lessened traction, braking and steering.

BTW, the Michelin Guide also says that an overinflated tire is more prone to impact damage

I am talking only about tires on a towable. Max sidewall inflation has been working for me for 30 years. No tire problems on my TT, ever.
Optimistic_Para
Explorer
Jul 30, 2019
sgfrye wrote:
drsteve wrote:
Inflate to max inflation as shown on the sidewall.

x2
no need to overthink it. has worked for me. autos, boat trailer tires, and motorcycles

As far as cars, vans, pickups, and motorized RVs go, inflate your tires to maximum and go to a mall before it opens. Use a piece of chalk to put a line across each tire, and drive a couple of hundred yards. Then check your tires. In most cases - depending of course on your vehicle weight - I think you will see that the chalk is worn off in the center, but not at the edges, which indicates that not all of the tire tread is making contact with the road.

It seems self-evident to me that this is NOT optimum for either steering traction or braking in the shortest distance. And I suspect you will also be more prone to hydroplaning in the wet than if your tires were making complete contact with the road.

Both Goodyear and Michelin have downloadable RV tire publications, available here:

Recreational Tire Care Guide

RV Tire Guide

They both warn against overinflating tires because of lessened traction, braking and steering.

BTW, the Michelin Guide also says that an overinflated tire is more prone to impact damage
wa8yxm
Explorer III
Jul 30, 2019
rvshrinker wrote:
Everything I read says tires should be inflated to Max psi. Is there general agreement on that? I plan to do whatever is safest and as of last evening, my tires are at 60 and Max is 80, so I have some filling to do.

Strange. this is the first time I have read that.. I've always read tire inflation should be adjusted by scaling the wheels (each wheel (not tire but wheel) and adjust per weight on the wheel.

THe tire does not say "Maximum Pressure XX PSI"

It says "Maximum load yyyy pounds at maximum pressure of xx PSI"
sgfrye
Explorer
Jul 30, 2019
drsteve wrote:
Inflate to max inflation as shown on the sidewall.

x2
no need to overthink it. has worked for me. autos, boat trailer tires, and motorcycles