Tire pressure settings

[dlfishing]

In another forum topic someone replied to my comment about using 80psi in my DX3 by saying I should fill them to the max rated...on my Michelin tires I think the max is 110 psi.
I have always utilized the tire manufacturers charts to pressure up my RV tires.
At a FMCA rally both Cummins rep and Freightliner rep said the same thing that I have always done. Attached is a copy of a page from the handout that was provided by Freightliner

[halla]

do you use 80psi all around or just on the front?

[dlfishing]

Originally Posted by halla

do you use 80psi all around or just on the front?

Since my weight distribution seems to be nearly the same on all tires, I had it weighed on a truck scale, I use the same on all tires.
I only know the total weight on each axel, I would like to one day to weigh the tires individually to see if the left and right are the same.
I had my RV fully fueled and loaded for a trip when I weighed it.

[halla]

cool, probably rides better at 80 than 110

[dlfishing]

Originally Posted by halla

cool, probably rides better at 80 than 110

Yes, it does ride better.
I had my RV serviced at a truck repair shop and they were ‘NICE’ enough to fill all my tires to 110psi. Drove my tire monitor crazy until
I corrected the pressures. So I was able to feel the difference.

[Webefine]

This has come up before, I agree with Dl 100%. You should have your rig weighed when fully loaded and set the air in your tires according to the manufacturer guide. Not only will it ride better but you should get better tire life, even though RVers with rigs like ours rarely wear tires out they just get old.
This isn't just a truck thing. Most car tires have a higher max pressure rating than what the door sticker says, this is because the manufacturer of that vehicle has determined that the pressure on the door sticker is what the tires need for the max weight of the car.

[RV Randy]

Originally Posted by dlfishing

In another forum topic someone replied to my comment about using 80psi in my DX3 by saying I should fill them to the max rated...on my Michelin tires I think the max is 110 psi.
I have always utilized the tire manufacturers charts to pressure up my RV tires.
At a FMCA rally both Cummins rep and Freightliner rep said the same thing that I have always done. Attached is a copy of a page from the handout that was provided by Freightliner
Attachment 165581

I agree, I would never just fill a tire to the maximum pressure. But in addition to loaded axle weight, you also need to consider impacts to handling. If you are loaded lightly and like the softer ride at 80 psi, that's OK. But the softer setting could also increase sidewall roll and leaning when cornering or when encountering stiff cross winds. With a leaf sprung front axle this can cause chassis steering. If you aren't happy with the lean and steering wheel movement you get in cross winds, trying bumping up your psi 5 psi at a time (all tires) to see if you get an improvement so you can find a happy median.

[dlfishing]

Wouldn’t you think the tire manufacturer takes all that in consideration!

[Bill Davis]

Originally Posted by dlfishing

Wouldn’t you think the tire manufacturer takes all that in consideration!

If you read what's on the tire it says what the maximum pressure is allowed on a cold tire. It doesn't know what vehicle it is installed on. Always use the manufacturers recommend pressure, never the max.

[hook47]

When contemplating a diesel pusher I was interested in the tire pressure issue from that segment of the RV'ing world. Not positive, too lazy to try and find it again, but I think Lazy Days had an interesting tutorial on this subject. IIRC if you couldn't weigh each tire individually, weigh the axle and divide by number of tires. Check the tire manufacturer's site for proper psi and add 5 psi to compensate for unequal loading.

Like I said, If I Remember Correctly..

[RV Randy]

Originally Posted by dlfishing

Wouldn’t you think the tire manufacturer takes all that in consideration!

For obtaining maximum tire wear, yes. For determining optimal handling, no. They have no idea what type of vehicles the tires will be used on. Optimal handling psi is probably different on a tractor trailer rig versus a straight frame rig. Is it a low profile vehicle or a box rig that is like a rolling billboard? Flatbed trailer, etc? Gravel hauling dump truck?

[Sunset beast]

Originally Posted by dlfishing

Wouldn’t you think the tire manufacturer takes all that in consideration!

Here is Michelins RV tire Care Use and maintenance guide. It's good reading. One good point in the material and that there has been a thread discussion on here is keeping equal tire psi across rear dual tires & dual axels, I'm using a Crossfire Equalization system with TPMS at 95psi which is giving me some peace of mind when on a long haul.

https://www.michelinb2b.com/wps/b2bc...s_Brochure.pdf

[dlfishing]

Originally Posted by Bill Davis

If you read what's on the tire it says what the maximum pressure is allowed on a cold tire. It doesn't know what vehicle it is installed on. Always use the manufacturers recommend pressure, never the max.

If you go online you can find load/tire pressure tables for most tire manufacturers. I know Michelin and Good Year has them

[dlfishing]

Originally Posted by RV Randy

For obtaining maximum tire wear, yes. For determining optimal handling, no. They have no idea what type of vehicles the tires will be used on. Optimal handling psi is probably different on a tractor trailer rig versus a straight frame rig. Is it a low profile vehicle or a box rig that is like a rolling billboard? Flatbed trailer, etc? Gravel hauling dump truck?

All of that is not the concern. It’s the profile of the tire hitting the road. Too much psi and you’re riding on the center of the tire, too little and you’re riding on the edges.
For all the reasons in the attachment to my original post you need the correct tire pressure regardless what they are mounted on.

[Coolbaldguy]

Another thing to take into account on the tire pressures is TEMPERATURE. Most Tire manufacturers load/inflation index assumes the ambient temperature of 70 degrees F. For every 10 degrees + or - one needs to factor about 2 psi. so if one is aiming for 100 psi pressure and it is 60 degrees out and the tire has not been used in several hours and the sun is not shining on it....then 98 psi would be the correct pressure. Of course that all goes out the window if they are nitrogen filled, which most of the G and H rated tires are not. Also one should never remove air pressure from a hot tire, because you just cant tell how much pressure there "should be" in it.

[Thebackpacker]

On my 2016 DX3, Model 35DS, there is a substantial difference in the weight on the left and right rear wheels. In such a case, according to Michelin, the pressure in all tires on the same axle should be the same and set for the tire(s) with the greatest load.

Wheel weights for my DX3, loaded for travel including passengers, was as follows:

Model: DX 35DS
Wheel Weight
RF.......4,350
LF........4,400
RR.......6,950
LR.......8,750
Total..24,450