Tire Inflation Table help please....

[lpkirby]

I purchased 6 new tires and the chart below is what Cooper emailed me for inflation's on the Road Master Tires. I am not sure if I am reading this correctly, I have the 225/70r19.5's. I cannot get a weight of each individual tire but I was able to get to the CAT Scales and I am at 5660 lbs in the front and 11620 in the rear. If I am reading this correctly then I need 70psi in the front and 80 psi in the rear. Is this correct?

load and Inflation Table for RMT tires .pdf

Thanks for taking the time to look at this...
Leon

[trackman]

I have that size and they recommended 90 all the way around when installed. I believe you need to have the same pressure all the way around what ever pressure you decide on.However You wil probably get quite a few different answers based on trail and error of individuals because of ride and gas mileage

[lpkirby]

Thanks trackman, I just found and read the post by MSHappyCampers on tire inflation and it answered some of my questions. I am just worried that 70 psi is not enough on the front. I also read to add 5 psi to my chart. I currently have them all at 90 psi, I would like to get them right before I head to the East Coast next week.
Thanks

[trackman]

I get a good ride and good (if you can call 8 per gallon good)gas mileage at 90. Have and safe and trouble free trip!!!!

[CLIFFTALL]

Originally Posted by lpkirby

I purchased 6 new tires and the chart below is what Cooper emailed me for inflation's on the Road Master Tires. I am not sure if I am reading this correctly, I have the 225/70r19.5's. I cannot get a weight of each individual tire but I was able to get to the CAT Scales and I am at 5660 lbs in the front and 11620 in the rear. If I am reading this correctly then I need 70psi in the front and 80 psi in the rear. Is this correct?

Thanks for taking the time to look at this...
Leon

That looks good to me. Personally , I would add 5 lbs for good measure.

Cliff

[georgetown350]

If you are choosing from the chart the psi based on your axle weight divided by two, you will most definitely be under inflated... not a good idea...... add 1000 lbs to your axle weight when looking it up on the chart and then buffer that by 5 lbs and you should be ok...... the axle weight is never proportioned evenly to each tire.... or you can just go by your gross weight until you get a chanced to weigh all corners...... better overinflated by a bit then under.....

[lpkirby]

Thanks everyone for the help..... So I set the air pressure to 75 on the front and 85 on the rear. We will see how this works out and I will monitor the heat and pressure with my TPMS.
Leon

[lpkirby]

Just a heads up, I got a call back from Cooper Tire this morning. He asked what my weight of my coach was and we went through the chart. He recommended going 10psi over the chart for safety concerns. So per Cooper, I am setting my tires at 80psi in the front and 90psi on the rears.
Thanks for all the help from everyone again....

[siggyd]

Keep in mind that when using the tire charts,the numbers are the MINIMUM
recommended tire pressures to carry the load.Always add 5~10 psi for safety.
Siggy

[georgetown350]

Keep in mind that when using the tire charts,the numbers are the MINIMUM
recommended tire pressures to carry the load.Always add 5~10 psi for safety.
Siggy

sorry to contradict but I do not agree that the numbers from the chart are the minimums. They are the exact recommended inflation for the weight of your rig.....which means you will not be under or overinflated....... we can all over inflate our tires by using our gross weight but we prefer to use the charts so as not to over inflate...... If I'm wrong I'm sure others will be willing to let me know....

[Old Coot]

Originally Posted by siggyd

Keep in mind that when using the tire charts,the numbers are the MINIMUM
recommended tire pressures to carry the load.Always add 5~10 psi for safety.
Siggy

Or just go to the max printed on the side of the tire and don't worry about it if you can tolerate the ride.

[lpkirby]

Originally Posted by dunnnc

Or just go to the max printed on the side of the tire and don't worry about it if you can tolerate the ride.

Wouldn't an over inflated tire wear badly? Over Inflated for the weight of the coach, not what is printed on the sidewall.

Leon

[Mr_D]

Originally Posted by trackman

I have that size and they recommended 90 all the way around when installed. I believe you need to have the same pressure all the way around what ever pressure you decide on.However You wil probably get quite a few different answers based on trail and error of individuals because of ride and gas mileage

No to the pressure needing to be the same all the way around. You do need to have the same pressure in all tires on an axle though.
The pressure given in the charts is the minimum required for the stated weight so you can go higher, but not lower.

[Mr_D]

Originally Posted by dunnnc

Or just go to the max printed on the side of the tire and don't worry about it if you can tolerate the ride.

The pressure on the sidewall of most RV tires is NOT the maximum it should ever have! It is the MINIMUM to support the maximum rating of the tire!!

ON TRUCK size tires the cold pressure on the sidewall is the MINIMUM required to support the maximum weight rating of the tires. Same with the tire charts, it's the MINIMUM cold pressure to support the weight. So YES you can exceed the pressure on the sidewall by a few psi

From page 2 of the 06/07 Michelin RV Tire Guide: "If you look at the tire's sidewall, you'll see the maximum load capacity allowed for the size tire and load rating, and the minimum cold air inflation needed to carry the maximum load."

From the Firestone/Bridgestone RV tire guide:

Bear in mind that these are maximum ratings. The sidewall of the tire shows maximum load and minimum inflation pressure for that load

From the GoodYear RV Tire Guide:

How much air is enough?
The proper air inflation for your tires depends on how much your fully loaded RV or trailer weighs. Look at the sidewall of your RV tire and you’ll see the maximum load capacity for the tire size and load rating, as well as the minimum cold air inflation, needed to carry that maximum load.

TOYO is one that does put the maximum pressure on the sidewalls of their tires though.