Truck tire pressure question

[twin88cam]

If your 5er hitch is installed correctly, you will actually increase the weight on your front tires by a small amount

[TxLoser]

I’ve never weighed my truck empty to compare. I just assumed....and you know what they say about that.

[Cheetah053]

I have a RAM 3500 I keep the tires at 80# cold when towing my 5th wheel.

[RickandBecky]

Originally Posted by Texdan25

Picking up my new fiver tomorrow with dry wt. of 9100# and GVWR of 11k. I have a 2013 Chevy 2500HD Duramax with Michelin 18" tires, max pressure rating 80lbs. I normally kept them at 70# when pulling my 7k bumper pull. Should I take the tires up to the max 80# since I'll have an additional 2500-4000#?

I have a 2020 30.5CKTS that has weight numbers very close to yours. Pulling it with a 2018 F250. I keep my tires at 65# when not pulling; 80#when loaded with our fifth wheel . Also keep 80# in the rig’s tires as well. Most tire experts would agree with this, I think. I know my tire shop that I’ve used for 30 years agrees this is best all around for truck and fifth wheel.

[CAG]

My 5th wheel was heaver than yours but 80 is the correct setting and unless you tow some high figure miles year the wear is minimal compared to the flex with the weight. The label weight numbers on your door jam are there for a reason. If you are going to take it to a scale, weigh each axle, calculate your load of food and clothes, divide by 3 and factor to the 10th, then set your pressure to the, who knows what then fine. Otherwise set them at the label pressure and forget it.

This just gets to be a joke after awhile. Sorry but that's what it comes to with some of this stuff.

[BxB62]

When I had the 5er I did 80 on the rear and 65 in the front per Ford towing recommendation. With the TT I do 80 all round.

[RickandBecky]

Originally Posted by BxB62

When I had the 5er I did 80 on the rear and 65 in the front per Ford towing recommendation. With the TT I do 80 all round.

Were these numbers from the Ford owner’s manual? I would think that with a fifth wheel’s hitch and weight being further forward in the bed of a truck, we would want to increase front tire pressures also. Just asking!

[Fleetman]

Originally Posted by billcf7

This is “chucking “ between pin box and hitch. Can be reduced with the use of rubber and/or air ride pin box and hitch

Moryde pinbox stops all that.

[Bill Johnson]

Originally Posted by Texdan25

Picking up my new fiver tomorrow with dry wt. of 9100# and GVWR of 11k. I have a 2013 Chevy 2500HD Duramax with Michelin 18" tires, max pressure rating 80lbs. I normally kept them at 70# when pulling my 7k bumper pull. Should I take the tires up to the max 80# since I'll have an additional 2500-4000#?

Question: From the 91% Rule above, if I want to ensure the tire can carry 2,367 lbs. capacity, then should I inflate the tire to the Max Pressure of 44 psi per the sidewall of the tire?

Answer: NO!

tire-placard

With P-Metric tires always follow the Vehicle Manufacturer’s specifications. Our Expedition tire pressure spec is 35 psi. Period.

Wow! So how much weight will each of my tires be rated to carry at 35 psi instead of the Max Pressure on the sidewall of the tire? Well… we have to look at the standards set by the TRA. Here they are below:

p275-65r18-load-pressure-chart

Notice that there is no tire pressure beyond 35 psi. Also notice that at 35 psi the max load is 2601 lbs. (or 91% = 2367 lbs. for SUV/LT/Van in the bottom row). So why does the side wall show Max Load = 2601 lbs. and Max Pressure = 44 psi?

Max Load is the maximum the tire is designed to carry, and since the tire meets TRA standards, it will carry 2601 lbs. at 35 psi cold temperature. There is no reason to add more air beyond the 35 psi recommended in our Ford Expedition Owner’s Manual; more air will not add additional load carrying capacity to the tire. Actually the Owner’s Manual states that the Maximum Air Pressure will be higher than Ford’s Recommended Air Pressure.

Many owners of SUVs, Light Trucks, and Vans that are running P-Metric tires are inflating them to the Max Pressure on the sidewall. They are not gaining capacity and do not understand that the recommended pressure on the door placard is the correct weight to handle the maximum capacity of the vehicle. Inflating a P-Metric tire to the Max Pressure may cause handling problems and will cause pre-mature tire wear in the center of the tire.

So why are the numbers (35 vs. 44) different?
The Max Pressure is the maximum pressure the tire is rated to hold. Let’s say you are going to store a vehicle for a couple years, and you want to inflate the tire as much as possible to allow for normal pressure loss over time. Then you would want to inflate the tire to 44 psi.

Sometimes a vehicle manufacturer will recommend a pressure higher than the 35 psi in this example for specific handling characteristics or use. An example might be a special use vehicle that never travels over 10 mph and is only operated on hard paved surfaces… perhaps a meter reader application.

Prove it!
Okay. A while back I wrote a post about trailer tongue weight. In it I shared the actual weights of the SUV’s axles and the Max Allowed by Ford. Here it is below.

expedition-axle-specs

The highest weight it at the rear drive axle. Ford specifies that the maximum the rear axle is allowed to carry is 4,250 lbs., or 2,125 lbs. per tire. That is well below the 91% Rule for the P-Metric tire the SUV was originally fitted with at 2,367 lbs.

Bottom line for our SUV using P-Metric passenger tires: the combined weight of the tow vehicle and trailer can be up to 15,000 lbs with the SUV tires set at 35 PSI. In our case we are towing a trailer weighing around 8,500 lbs. and a hitch weight just under 900 lbs. Tire Rack.com http://popupbackpacker.com/tire-pres...-tow-vehicles/

[Vista]

This thread reminds:

Knowing a little bit of information is a dangerous thing. So is sharing it.


One thing I know: Optimal PSI loading process differs between LT, P metric, or metric series tires, though folks assume all three are the same.

[CAG]

Originally Posted by Vista

This thread reminds:

Knowing a little bit of information is a dangerous thing. So is sharing it.


One thing I know: Optimal PSI loading process differs between LT, P metric, or metric series tires, though folks assume all three are the same.

Boy you got that right!!


There may be some that will go through all of that mental gymnastic exercise to air tires but that's why they put the pressures on the door jam and on the side of the tire. So you don't have to.

[billcf7]

Originally Posted by twin88cam

If your 5er hitch is installed correctly, you will actually increase the weight on your front tires by a small amount

With the new GM HD trucks the puck system is mounted 2 inches behind the rear axle so there is no way to install hitch to increase weight on front axle

[VKC]

Agreed. Run what’s on the door face

[Bill Johnson]

I agree my motorhome calls for 82 pounds cold on a sticker by the front window driver's side. The people that built the motorhome came up with that pressure, they should know what they are doing. When I got it from camping world yesterday they had 76 in each tire and I asked him the pressure he didn't know, that's what I like about them ask a question they say they don't know. One thing I like is the rear wheels have valve stems mounted near the center of the wheel, no need to remove the hubcaps anymore