Larger tires and PSI

wa8yxm wrote:

Tireman9 wrote:
because the tires are not turning and pointed toward the center of the ture circle.

Please explain, Thank you.. Epically the "Not pointed toward the center of a true circle" part... They should be pointed tangentially to a true circle,

Sorry for not being clearer. This may help


Increasing the inflation pressure will decrease the slip angle which will also decrease the "inter-ply shear" or the forces that are trying to tear the belts apart.

Make sure your wheels are rated for whatever pressure you are going to use...assuming you are operating at a higher pressure than OEM tires.

wa8yxm wrote:

Tireman9 wrote:
because the tires are not turning and pointed toward the center of the true circle.

Please explain, Thank you.. Epically the "Not pointed toward the center of a true circle" part... They should be pointed tangentially to a true circle,

While I am not Tireman9, I am a colleague of sort. Perhaps I can explain where he is coming from.

First, the axles on a trailer are parallel, so the tires can't be tangential when the vehicle is going around a curve. Each tire is at some angle to tangential and each is different.

Second, in order to develop a side force to turn the mass of the vehicle, the tires have to develop a slip angle - a difference between the direction the tire is pointed vs the direction it is actually rolling. When going around a corner all these slip angles are away from the direction of travel, so that makes the situation actually worse (and more complicated.) If you draw the lines, you'll find the resulting vector is aft of the axle centerlines.

Tireman9 wrote:
because the tires are not turning and pointed toward the center of the ture circle.

Please explain, Thank you.. Epically the "Not pointed toward the center of a true circle" part... They should be pointed tangentially to a true circle,

MM49 wrote:
Go with the max pressure. When you weigh a RV on a truck scale you get a weight of the total axel. You really need left to right weight also. Many times RV's are not balanced. My RV wore the tires out faster on one side because of loading. All of the equipment.kitchen, fridge, furnace and pantry are on that side.
MM49

X2...I remeber learning about high performance suspension setups when I was younger and the one thing that left an impression was balnceing the suspension which is basically putting the vehicle on 4 scales to measure the weight of the suspension and adding or removing shims to equalize the suspension.

Go with the max pressure. When you weigh a RV on a truck scale you get a weight of the total axel. You really need left to right weight also. Many times RV's are not balanced. My RV wore the tires out faster on one side because of loading. All of the equipment.kitchen, fridge, furnace and pantry are on that side.
MM49

poncho62 wrote:
Thanks...I went to the Goodyear site and they recommend running the tires at the pressure on the sidewall...65 PSI

Best recommendation, ever.

Thanks...I went to the Goodyear site and they recommend running the tires at the pressure on the sidewall...65 PSI

Proper inflation for Motorhomes is usually based on actual load on the tires but inflation on multi-axle trailers is different because the tires are not turning and pointed toward the center of the ture circle. This puts high loading on the structure. To lower this extra load you should run the tire sidewall inflation to get the best life possible from your tires.

"Technical babble" info can be found if you Google
interply shear RV tire

Check the tire manufacturer's web site to see if they have any info on inflation, I'll bet they do. There may be a chart for inflation vs weight. If you're not running near the max weight on the tire you probably don't need to inflate them to the max psi. Then again, that may be what they recommend.