tow vehicle tire pressure

[NomadBD]

Hello all,

My TT manufacturer recommends inflating the tow vehicle rear tires to maximum cold pressure listed on the side wall prior to towing. I've always gone of the pressures listed on the sticker located on the inside of the vehicles driver side door.

Thoughts?

Thanks,
Nomad

[IWillRVToo]

You must use the numbers from the sidewall of the tire.

[450Donn]

You dont have to but it is wise to use tires max pressure printed on the sidewall.

[RustyJC]

Your TT manufacturer is trying to minimize any propensity for trailer sway by ensuring that the sidewalls of the tow vehicle's rear tires are as stiff as possible - thus, the recommendation to inflate to maximum cold inflation pressure shown on the sidewall. Is it necessary - I guess it depends on the effectiveness of your sway control arrangement and the tendency of your particular tow vehicle/trailer to sway.

Rusty

[NomadBD]

Interestingly, I have never had a problem with sway control. This, and my load levelers do a great job.

Looks like I will be inflating to max pressure. Should I do the same for the front tires as well?

Again, thank you all for the great advise.

[schrederman]

I run my vehicle tires at max cold pressure as listed on the sidewall at all times. I have 20 vehicles in a fleet and 2 personal vehicles. Our tires wear better and our gas mileage increases slightly from the higher pressure in the tires...

[SmokeyWren]

None of the above.

LT tires should be inflated to the PSI required to carry the weight on the tire. To do it right you need to know the weight on the tire and have the load/inflation table for that size tire handy.

For example, a late-model Ford F-150 with the HD payload pkg has LT245/75R17E tires. Here is the load inflation table for those tires:

PSI . max weight
__ . --------
35 . 1770
40 . 1945
45 . 2110
50 . 2270
55 . 2430
60 . 2595
65 . 2755
70 . 2900
75 . 3050
80 . 3195

It's okay to inflate the tire to 5 or 10 PSI more than indicated in the load/inflation table, but more than that and your ride deteriorates and the center of the tread wears out faster.

Example: A recent CAT scale of my rig with the WD hitch hooked up showed I had 3280 on my front axle, 3620 on my rear axle (6800 GVW compared to 7200 GVWR) and 3620 on the trailer axles (10,420 GCW compared to 14,000 GCWR). Or 1,640 on each front tire, 1,760 on each rear tire, and 905 on each trailer tire. If I had those tires LT on the pickup, then applying the table, I needed only 35 PSI in each tire, front and rear, to safely handle that load. Pumping up the tires to 45 PSI all around would give me 4,220 pounds of tire weight capacity on each axle. Pumping the tires up to the 80 PSI on the sidewall would be madness.

P-Series (passenger car tires) are different. My F-150 door sticker says to inflate my stock P265/60R18 tires to 35 PSI all around. That will be plenty if I don't exceed the GVWR of the pickup. But I'll pump them up to the max of 44 PSI when towing on long road trips.

[Mr_D]

For a TT or 5th wheel the tire manufacturer says to inflate to the max pressure on the sidewall especially with ST tires.
This is different than for motorhomes.

[SmokeyWren]

Originally Posted by Mr_D

For a TT or 5th wheel the tire manufacturer says to inflate to the max pressure on the sidewall especially with ST tires.

Maxxis publishes the load/inflation table for their ST (trailer) tires. So that's at least one tire manufacturer that disagrees with you. Click on the following link to see the load/inflation table for Maxxis ST tirews:
http://www.maxxistires.com/Repositor.../m8008load.pdf


Granted, nost trailer manufacturers say to inflate the trailer tires to the max - but that's because they usually include stock trailer tires that have to be inflated to the max to support the GVWR of the trailer.

[FastEagle]

Originally Posted by SmokeyWren

Maxxis publishes the load/inflation table for their ST (trailer) tires. So that's at least one tire manufacturer that disagrees with you. Click on the following link to see the load/inflation table for Maxxis ST tirews:
http://www.maxxistires.com/Repositor.../m8008load.pdf


Granted, nost trailer manufacturers say to inflate the trailer tires to the max - but that's because they usually include stock trailer tires that have to be inflated to the max to support the GVWR of the trailer.

Maxxis is one of the very few ST tire manufacturers that allow the use of various load inflation pressures for their ST tires. You can call or email your area Maxxis tire rep and get the canned answer - from a live person. They will tell you that they only support tire inflation pressures set/recommended by the vehicle manufacturer.


FastEagle

[FastEagle]

Originally Posted by NomadBD

Hello all,

My TT manufacturer recommends inflating the tow vehicle rear tires to maximum cold pressure listed on the side wall prior to towing. I've always gone of the pressures listed on the sticker located on the inside of the vehicles driver side door.

Thoughts?

Thanks,
Nomad

This might sound harsh but it’s the truth. That travel trailer manufacturer has no business recommending tire pressures for your truck. They didn’t build it. All the information needed to establish the towing pressures for your truck can be found in the owner’s manual and/or the tire placard. If in doubt ask the truck manufacturer.

FastEagle

[JimM68]

Originally Posted by FastEagle

This might sound harsh but it’s the truth. That travel trailer manufacturer has no business recommending tire pressures for your truck. They didn’t build it. All the information needed to establish the towing pressures for your truck can be found in the owner’s manual and/or the tire placard. If in doubt ask the truck manufacturer.

FastEagle

Not only harsh, but probably dead wrong.

As was stated above, the tire needs to be inflated to carry the load according to the tire manufacturers load/pressure charts.

And you should wiegh the vehicle, with and without the trailer hooked up.

Remember the exploding firestone explorers?
No way in he double hockey sticks I would trust or rely on (particularly Fords) tire pressure recommendations when operating a vihicle at or near max loading.

[FastEagle]

Originally Posted by JimM68

Not only harsh, but probably dead wrong.

As was stated above, the tire needs to be inflated to carry the load according to the tire manufacturers load/pressure charts.

And you should wiegh the vehicle, with and without the trailer hooked up.

Remember the exploding firestone explorers?
No way in he double hockey sticks I would trust or rely on (particularly Fords) tire pressure recommendations when operating a vihicle at or near max loading.

Regardless of personal opinions what I said is the industry standard. I seriously doubt a tire manufacturer, any tire manufacturer, would openly argue tire pressures with a vehicle manufacturer, an vehicle manufacturer. The DOT says vehicle manufacturers set tire pressures for their vehicles.

Most untrained people using tire load inflation charts to adjust their tire pressures do not know how to apply the correct pressures. Here is a short PDF from Bridgestone that explains most of the correct procedures. It clearly says the vehicle manufacturers recommended tire pressures found on the tire placard/certification label are the minimum standard to work from.


http://www.trucktires.com/bridgeston.../WeighForm.pdf

Note: Motorhome tires are fitted to accommodate the vehicle’s GVWR. RV trailer tires are fitted to accommodate the vehicles’ certified GAWR.

OOPS! Forgot to mention. Automotive vehicle tires - cars, pick-ups, SUVs etc... - are mandated by the DOT to have a minimum amount to load capacity reserves.
FastEagle