Tire pressure question

[dougandrobin]

I have a 40ft Landmark. Tires say 110lbs max pressure. Should I make them up to the max of 110lbs when cold? Right now they are about 98lbs.
TIA

[FastEagle]

Originally Posted by dougandrobin

I have a 40ft Landmark. Tires say 110lbs max pressure. Should I make them up to the max of 110lbs when cold? Right now they are about 98lbs.
TIA

You should inflate them to the pressure recommended in your owner's manual, on the tire placard and certification label.

FastEagle

[samschudi]

I think the key here id enough pressure where the face of the tire rides flat to the road surface, with minimal sidewall deflection. 98 lbs may be perfect, depending of how much weight the tire is carrying on your loaded MH. Think of it this way, at 110 lbs pressure, the tire can carry the maximum recommended weight as listed on the sidewall. Not likely it is loaded that heavy, plus the tire pressure will increase as the tire heats up.

[justafordguy]

What model is the landmark? Also what is the gvw? I always inflate to the max marked on the tire.

[CampingCajun]

You should get axle weights on your 5ver & then check the manufacturers inflation chart & air them up accordingly. That is the best way to get inflation pressures.

[JIMNLIN]

Using a minimum pressure from a tire chart isn't the best idea for a tire on a trailer for several reasons.
The biggest reason industry experts and tire manufacturers recommend max sidewall pressures is internal ply shear forces.
Tires on a multi close spaced trailer axle system in the center of a heavy box actually slide sideways at the trailer is pulled around the corner (side scrubbing).
Max pressures help hold the tires shape and helps reduce shear forces at work.
Cooler operating and a host of other reasons.

I think Goodyear website says it best;

Goodyear Tire and Rubber .... weighing RVs
Special Considerations

Unless trying to resolve poor ride quality problems with an RV trailer, 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

[FastEagle]

Here is a reference for the proper use of tire load inflation tables.

Tires 101: Tire Load & Inflation Tables | Toyo Tires

FastEagle

[dougandrobin]

Thanks all!

[FastEagle]

I took some pictures at a RV show some time ago. I was impressed with the tire fitment on this Landmark. Goodyear G114 17.5" LRH.

Greenville_RV_show_-_1-2015_31_ - iRV2.com RV Photo Gallery

FastEagle

[taken]

Originally Posted by CampingCajun

You should get axle weights on your 5ver & then check the manufacturers inflation chart & air them up accordingly. That is the best way to get inflation pressures.

This is what I've been doing. I second guessed myself after reading JIMNLIN's answer so I called Goodyear direct. I have the G614's that I run at 95-100 psi based on the load inflation chart and my 7k axles. Goodyear confirmed that you always go by the load inflation chart and not go with max sidewall listed pressure. I did mention what Jim posted about their RV guide saying that but they told me to go the other way. I guess it's dealer's choice since they post the info both ways...

[FastEagle]

Setting the recommended tire inflation pressures for your Original Equipment tires (OE) is the sole responsibility of the vehicle manufacturer. That is written into the DOT tire safety regulations. Tire manufacturers will - in the end - always agree with that. In the reference below Goodyear has done so.

Tire Pressure Basics | Goodyear Auto Service Center

On the other hand, replacement tires that are a different size than the OE tires all have the same rule. They must provide the same load capacity as the OE tires. That is when the load inflation tables are needed the most, to determine the amount of inflation pressure needed in the replacement tires to get the needed load capacity from them.

FastEagle

[JIMNLIN]

Originally Posted by taken

This is what I've been doing. I second guessed myself after reading JIMNLIN's answer so I called Goodyear direct. I have the G614's that I run at 95-100 psi based on the load inflation chart and my 7k axles. Goodyear confirmed that you always go by the load inflation chart and not go with max sidewall listed pressure. I did mention what Jim posted about their RV guide saying that but they told me to go the other way. I guess it's dealer's choice since they post the info both ways...

I've mentioned it to the 1-800 folks and they had no idea that it was there on their website nor did they understand about inner ply shear/side scrubbing issues and close spaced axles/tires on trailers. After all their in the business to sell you a tire.
However experienced trailer owners and RV tire blogs recommend max pressures in tires on a conventional trailer with axle in the center. Now a interstate trailer type with tires at the corners don't side scrub so a minimum pressure works for them.

More reading on the subject from the pros;
Step 5 - Tire Loads | RV Tire Inflation Procedures . 5th wheel street at one time did recommend a minimum pressure chart for trailers but woke up and no longer recommend doing so.

and from a actual tire engineer;
RV Tire Safety: Inflation. Scroll down about 2/3rds to the bottom and see his info on interply shear forces on a trailer.

Never heard of derating a tire on a trailer till I started hanging out on RV websites.

[3ares]

Tire air pressure should be what is stated for the weight of your trailer per the charts. There is a red neck way of using the proper air pressure-rub chalk across the tread about an inch wide and pull the trailer a short distance and check the chalk mark. If the chalk mark is worn evenly the air pressure is pretty close.

Happy Camping

[glennwest]

Originally Posted by 3ares

Tire air pressure should be what is stated for the weight of your trailer per the charts. There is a red neck way of using the proper air pressure-rub chalk across the tread about an inch wide and pull the trailer a short distance and check the chalk mark. If the chalk mark is worn evenly the air pressure is pretty close.

Happy Camping

Only way to accurately do this is weigh each wheel individually. I haven't. Only used cat scales. So I weigh at max per tire rating.