Tire pressure issue

[bzp]

Seeking advice concerning the best tire pressures for my motorhome. I have a 2004 Winnebago Journey that is built on an oversized Freightliner chassis. The chassis GVWR is 27,900# and my coach weighs in at 21,180# fully packed and filled with liquids. I have Goodyear G670RV tires (26575R22.5G). Winnebago says I should have 100 psi in the rear tires and 105 psi on the front tires. I checked the Goodyear website and found that the 100/105 psi recommended tire pressures would be right if my coach weighed 29,519#.

I believe the Winnebago recommended pressure is too high because it was selected to cover my GVWR rather than the actual weight of my coach. The Goodyear inflation / load charts say I should use only 75 psi.

What is the best pressure for my tires? I believe a reduced pressure will give me a smoother ride but I question how the reduced pressure will affect my steering and handling. I am also concerned about making such a significant change without advise from other experts.

Does anyone have experience and recommendations?

[bzp]

Thanks.

I see a smoother ride in my future.

[rgatijnet1]

bzp wrote:


Does anybody know how the reduced pressure will effect my corner handling and straight line tracking?

It should be exactly as the tire was designed since you would be running the tire within the manufacturers design specs.
In fact I would expect it to be better than when you were running the tires over-inflated.
Naturally tire pressure has nothing to do with wheel alignment of both axles.

[bzp]

Thanks for the input. This will give me some peace of mind when I reduce my tire pressures. I did weigh the axles using a CAT scale and will try to find a place to weigh all four corners. Until then, I will run my tire pressures 10 psi above the Goodyear minimum for each axle. This will be a 15 or 20 psi reduction from current pressures and should give me a much softer ride.

Does anybody know how the reduced pressure will effect my corner handling and straight line tracking?

[CapriRacer]

hohenwald48 wrote:
I don't think that is a correct statement. As far as I've ever seen, all tires of the same size, type and load range use the same pressure for the same load. It is not brand specific.

That is more or less correct. There is some variation between different tire standardizing organizations - where the tire manufacturers get those values - but the variation is small - and small enough to ignore.

[hohenwald48]

I don't think that is a correct statement. As far as I've ever seen, all tires of the same size, type and load range use the same pressure for the same load. It is not brand specific.

[10forty2]

Different tires require different pressures. Michelins require different pressures than Goodyears, Goodyears require different pressures than Bridgestones, Bridgestones require different pressures than Toyos, and so forth and so on. That's why each tire manufacturer has a pressure chart. As said, weigh the rig as you would normally travel, and set the pressures according to the tire manufacturer's chart for that tire at that weight.

[Effy]

Lwiddis wrote:
"I believe the Winnebago recommended pressure is too high because it was selected to cover my GVWR rather than the actual weight of my coach"

Every tire maker I know says "Follow the RV manufacturer's tire pressure instructions." My recommendation....follow Winnebago's guidelines.

Not sure I've ever read that. Any tire manufacturer I've dealt with says to go by their weight chart.

The ONLY way to get proper PSI is to load your rig for travel (Including fuel, water, people, food, etc) and weigh it - 4 corners if you can - and adjust PSI based on the TIRE manufacturer's chart.

The stickers put on the MH at the time of manufacture have no clue how you will load your rig for travel and are a worst case scenario. Conservitive - yes, accurate - no.

[1492]

Moved from Forum Technical Support

[Ivylog]

Welcome and this type question comes up often... post in the Class A section. The best is to weigh all four corners BUT it's hard to find a place that lets you get off to the side while on the scale. Next best is axle weights at a truck stop with Cat scales, most land fills, a rock quarry, or even a large feed mill. You want to weigh your rig loaded up to travel with full fuel and water and then go to the load tables for your tires to find the correct pressure.

A moderator will move it to Class A.

[Lwiddis]

"I believe the Winnebago recommended pressure is too high because it was selected to cover my GVWR rather than the actual weight of my coach"

Every tire maker I know says "Follow the RV manufacturer's tire pressure instructions." My recommendation....follow Winnebago's guidelines.