Tire Inflation Guide

Cummins12V98 wrote:
Jim your HR came with E tires correct? They recommended max pressure at 80 psi correct? The G tire Carries the same load as the E at the same pressure. So to say HR wants you to run 110 psi on your G tires does not sound right.

Run what you want it's up to you but talk to GY tech they will tell you that you can use the charts for proper inflation based on load when up sizing the load rating.

Shouldn't the wheels be rated for the higher pressure also?
Rich

Jim your HR came with E tires correct? They recommended max pressure at 80 psi correct? The G tire Carries the same load as the E at the same pressure. So to say HR wants you to run 110 psi on your G tires does not sound right.

Run what you want it's up to you but talk to GY tech they will tell you that you can use the charts for proper inflation based on load when up sizing the load rating.

blt2ski wrote:
Jim,

I do this for the trucks, trailers I run at max sidewall pressures. My trucks, especially the rears. The 70 or 75 series tires we seem to be getting on newer rigs today is more susceptible to the middle wearing out if you run max psi and then run the rig empty for long periods say commuting. A pizza cutter tire, ie an 85 series this does not seem to be an issue. I was able to run 70 psi in a 235-85-16 empty on a pickup and get full tire width contact, where as a 245-75-16 was in the 55-60 range. Both tires have the same total wt at psi etc per a tire chart.

My old dually, I only need 50-55 when empty, then again, it only had 3-3200 lbs on it. Single tired rigs seem to have 2100-2400 ont he RA, so again, no need to have full psi. Rides really rough too.

The visual with water, dust etc seems to give me a pretty good clue if I have too much psi in the tires. I have never weighed ea tire. I do go thru the DOT scales to see how I am doing on axel wts at times. but otherwise, no need to weigh, as ea trip will be slightly different per say.

marty

Marty
I'll go with you on that Marty and it sounds like you got your system, "down pat".. and as you stated, weights can change....I've weighed my 5er when loaded light and when loaded heavy...still run 110 psi in the G rated tires, as recommended by both HR (though now out of business with 5er's), and with Goodyear....truck tires are a different subject..


thanks for the explanation,
Jim

Jim,

I do this for the trucks, trailers I run at max sidewall pressures. My trucks, especially the rears. The 70 or 75 series tires we seem to be getting on newer rigs today is more susceptible to the middle wearing out if you run max psi and then run the rig empty for long periods say commuting. A pizza cutter tire, ie an 85 series this does not seem to be an issue. I was able to run 70 psi in a 235-85-16 empty on a pickup and get full tire width contact, where as a 245-75-16 was in the 55-60 range. Both tires have the same total wt at psi etc per a tire chart.

My old dually, I only need 50-55 when empty, then again, it only had 3-3200 lbs on it. Single tired rigs seem to have 2100-2400 ont he RA, so again, no need to have full psi. Rides really rough too.

The visual with water, dust etc seems to give me a pretty good clue if I have too much psi in the tires. I have never weighed ea tire. I do go thru the DOT scales to see how I am doing on axel wts at times. but otherwise, no need to weigh, as ea trip will be slightly different per say.

marty

blt2ski wrote:
An E rated tire of the same size as a D rated tire, will carry the same load at the same pressure up to the max of the D rated tire. The E rated tire has the ability to carry a higher pressure, hence a heavier load.

A tire pressure load chart works, I use the chalk method. Ie put some tire chalk on the tread, drive down the road, if all of the chalk goes away in a 100 yds or so, you either have the correct pressure, or too little. If a partial goes away, ie the middle only, you have too much psi. You can see the same effect after going thru a puddle and stopping a few yds later, or if the middle has dust, the outer does not.....

Not sure there is truly a right or wrong way per say. Other than, not fun to see the middles wear out of the tread before the outer. Then you know you had too much psi, and wore out the tire too soon!

marty

Marty..WAYYYY to much work and I'm not lazy...Pretty doggone sure from what I've gleaned from Michelin, Continental/General and Goodyear, that running at sidewall max recommended psi will NOT cause issues with the tire...IF used as an E or G rated tire in replacement of an E or G rated tire..... I've never seen the middle of my tire wear abnormally....

Again, if one has the time and equipment to weigh each tire, have at it, but I'm not hooking up and running back and forth over something to check tire pattern AND I don't have access close by, or the time, to find a place where I can get each tire weighed....I'll go by manufacturers recommendations and again, the GY G614's on my 5er now, run at 110 psi and look as good as they did the day they were put on my 5er in Oct. of 2010....

An E rated tire of the same size as a D rated tire, will carry the same load at the same pressure up to the max of the D rated tire. The E rated tire has the ability to carry a higher pressure, hence a heavier load.

A tire pressure load chart works, I use the chalk method. Ie put some tire chalk on the tread, drive down the road, if all of the chalk goes away in a 100 yds or so, you either have the correct pressure, or too little. If a partial goes away, ie the middle only, you have too much psi. You can see the same effect after going thru a puddle and stopping a few yds later, or if the middle has dust, the outer does not.....

Not sure there is truly a right or wrong way per say. Other than, not fun to see the middles wear out of the tread before the outer. Then you know you had too much psi, and wore out the tire too soon!

marty

As I have said here before. Contact GY Tech Support for what they say. I did when going from GY E to GY G. They said to use the chart on RV for STOCK RATED TIRES. But if you are up rating the tires use the inflation chart for your new tires and add 5psi. For example my RV said 80psi and my load need that psi, surprise surprise! Now with the G tires the load still needed 80psi but by adding 5 psi I was at the proper tire inflation for the tire.

They said they defer to RV label when stock tires are replaced with stock but the charts are there for a reason. They also said too much air as in 110psi for my load will give a more harsh ride along with less stopping traction.

I used GY inflation method for 5 years and a lot of miles with perfect tire wear and never a problem.

past-MIdirector wrote:
Need to look at the load range on the replacement tires. Most RV replacement tires are one or two load ranges high with a higher max. pressure then what was originally put on. I was taught many moons ago that to be safe air tires to 10% of what the max. pressure is on the tire. This has worked for 40 years now.

Well, I'll admit I've never done that, I've alway's aired to max sidewall rated psi...never added an extra 10% which would be loading a Michelin "E" rated RIBS to 88# instead of 80 and airing my GY G614's to 121 psi instead of the recommended 110psi...one could do that, but again, I've been towing since 75, (and some before that), and also never had an issue... and thats worked for me for almost 40 years also...

My experience has seen most newer RV's with tires on them that are "just close" enough to cover axle rating...as little as the manufacturer can get away with and cut corners on cost. It's rare that I've seen a "G" rated tire where an "E" rated tire would have worked...it's very, very rare.

The quality of the 'ride' is partially dependent on tire pressure. The tire mfg site gives you the minimum pressure to carry the weight, while the tire sidewall gives you another maximum pressure. Also, the coach mfg gives you a sheet with their "recommended" pressure. In general, the lower the tire pressure you have, the smoother the ride you will have.

For example, on my coach, I have Michelins and I know the loaded weight on each corner. According to the Michelin charts, I can carry 85 pounds on the front tires and 90 pounds on the back. The max pressure listed on the tire is something like 115, and the mfg chart recommends 110 front and back. I chose to carry each tire at 95 pounds which seems like a compromise all around plus I get a good ride at that pressure.

I ran my calculations past the dealer, who said "huh?". I called the Monaco and talked to them. They confirmed my calculations and my decision to carry 95 pounds pressure.

These are load rating charts not recommended pressures. All they do is give the maximum load a tire can carry at a certain pressure.