Tow Vehicle Tire Pressure

[CatFlip]

I have replaced my P rated tires with E rated tires. The recommended tire pressure on the truck sticker says 35PSI. This is for the P tires. The max tire pressure on the side of my new E is 80PSI. What would you recommend my unloaded and loaded tire pressure should be for my new E tires? I am thinking 50PSI unloaded and 70 or 80 loaded?

[Lloyd]

How much weight is your trailer putting on your truck?

[CatFlip]

I am not sure on the pin weight yet. I am taking it out today on our first trip. I am thinking about 1,800LBS.. I will be taking it to a scale this weekend.. With this weight I am thinking I should go with 80PSI?

[Lloyd]

With just the 5th wheel pin weight I'm not that heavy, but when I load stuff in the truck bed, I probably get pretty close to that figure.
I run 50-55# MT and 70# loaded. I tried it with more pressure and the ride was pretty rough, so I dropped the pressure.
If you look at the sidewall it will tell you what the load rating is. I was way under that, and my tire dealer said I wouldn't have to max out the pressure.

I would think your rig will be way heavier then mine. It's better to pull on a scale and find out for sure rather than guessing.

[harley]

I am only towing a TT that is 30 ft total and a hitch weight of around 1000#. I left the tires the way they were when I got it(70#) on rear and wore the center of the treads on both rear tires . Obviously too much pressure. Next time its going to be 50-55#. And the ride will be better.

[Lloyd]

harley, are talking MT, loaded, or leaving it at 70# all the time?

[Russb]

The tire mfg should have a weight/pressure chart. Try their website or your dealer for the info.

[CatFlip]

Thanks for the help. I just put in 70PSI front and rear. I have stock rims with rubber valve stems. Kind of worried if the rubber stems will take 70PSI. I could not find any Max PSI for the rims. I will see how this rides. I am only going for a short 15 mile local trip to see how everything works. I will weight everything to get a better idea what my pressure should be.

[harley]

Originally Posted by Lloyd

harley, are talking MT, loaded, or leaving it at 70# all the time?

My last short trip (before I sold the 3/4 ton) was set at 55 and rode nice and didn't swagger. Did not notice any difference in swayage from the 70#. Left it at 55 empty and was happy. Onstar didn't like it and kept getting messages....

[longhauler]

I have also heard the more air pressure in your tires the better your fuel mileage will be. Not sure how much difference it makes. I run my tires at max air pressure in the summer months and 50 lbs rear and 60 lbs front in the winter.

[avvidclif]

Originally Posted by CatFlip

Thanks for the help. I just put in 70PSI front and rear. I have stock rims with rubber valve stems. Kind of worried if the rubber stems will take 70PSI. I could not find any Max PSI for the rims. I will see how this rides. I am only going for a short 15 mile local trip to see how everything works. I will weight everything to get a better idea what my pressure should be.

I wouldn't worry about the stems as much as the rims. Are they rated for 80psi. Mine is a 1T SRW and the placard shows (loaded) 60 front and 80 rear and that is on stock E rated tires. Myself I would weigh the actual load (F&R) then find the load chart for those tires and set to the chart. The 60 PSI in the front is for that chunk of lead called a diesel engine. I actually have almost 5k on the front axle MT and the 60 PSI is for that. The 80 PSI on the rear takes it up to almost 7k.

[Russb]

This link has info on valve stem pressure ratings.
http://www.tirerack.com/tires/tirete...jsp?techid=208

[Tim D]

Originally Posted by longhauler

I have also heard the more air pressure in your tires the better your fuel mileage will be.

Rolling resistance is less if your tires are "properly" inflated thereby improving gas mileage. How much? IDK. As someone else said, there should be a load chart to recommend PSI based on weight.

[DavisK]

Chevrolet says 60 psi in the front and 70 psi for the rear of my Silverado. I keep it at that all the time. The hitch weight of my SF270BH is just over 1000 lbs.

[johnboytoo]

do a google search for the tire chalk test...
this will tell you how to set your psi on YOUR tires, on YOUR truck, for YOUR load, and YOUR conditions...

basically lets you know if your tires are riding flat across where they are bet for traction, wear, and longevity versus concave or convex...

and here are the tire inflation charts for a starting point for your weights:
https://www.google.com/search?q=good...en-US:official

[mark5w]

No matter if you use 70 or 80 lbs of pressure, I would use the metal valves that are rated for the higher pressure. If you used the stock P valves, I'm not sure they are rated for the higher pressure.

[CatFlip]

I weighted everything at the scales and that has made me a little concerned. I never considered the GAWR and was only concerned with the max towing capacity when we purchased the RV. GAWR is 3,900 lbs. The loaded pin weight is 2,020 lbs. My rear truck axle weighs 4,920 lbs with the trailer. That is 1,000 lbs over GAWR. Will the upgraded E rated tires and air bags help? Braking performance seams great with the help of the electric trailer brakes. We are close to but under GCWR and Max trailer towing capacity of 10K but my concern is mainly the GAWR and having rear axle failure in the future. Are there any upgrades that can be made to the rear axle?
Phil

[johnboytoo]

Don't beat yourself up for that Many miss the rear axle loading and the dealers won't tell you that (neither the rv or truck dealer !)
Dunno how you are loaded,
but can you enough of the weight around to lessen the rear gaw ?

Air bags will level out your tv, but they won't added any load carrying increase to the equation.

[CatFlip]

Not sure if moving the weight around will help. The advertised dry hitch weight of the SF32RL is 1,898 lbs. I am only 100 lbs over that. I do have stuff stored up front but nothing heavy. All gray/black tanks are empty. With only being 100 lbs over the dry hitch weight I don't think cargo weight distribution is the issue. TV rear weight without 5er is 2,900 lbs. Dodge says the base rear weight is 2,358. That is about 600 lbs over. The Superglide might weigh 200 lbs of that. Then fuel and the weight of my son and I in the cab. Maybe I should go to another scale and just weigh the TV alone to compare.

[sleepyT]

Cat
I agree with Russ and start with the manufacturer web site. I would also start with their loaded pressure. As far as the unloaded pressure I would start with their pressure and watch the wear on the tires. IMHO