What is correct the tire pressure?

[namwob]

How do I determine the correct tire pressures for my MH? Is there a chart that brings together the factors of tire size and vehicle loads to determine the best tire pressure to use?

The original tires on my 1999 Monaco Windsor were replaced with 295/80R22.5 LR H G391 tires. How did this change the recommended tire pressure? My front axel weight is 10,600 lbs and the rear is 18,300 lbs. Also what do the numbers/codes represent on tire size?

[Jim Stewart]

Here is the Goodyear Information on load and pressure, it's big, so it takes awhile to download.

http://www.goodyear.com/truck/pdf/edb_loads.pdf

[WeatherTodd]

recommended pressures should be embossed on the tire sidewall.

[chiefdave]

The date of manufacture is indicated by the last group of digits in the DOT manufacture code on the sidewall of the tire. The number is often stamped in a recessed rectangle. The DOT code tells who manufactured the tire, where it was made and when. The last group of digits in the code is the date code that tells when the tire was made.
Before 2000, the date code had three digits. Since 2000, it has had four. The first two digits are the week of the year (01 = the first week of January). The third digit (for tires made before 2000) is the year (1 = 1991). For most tires made after 2000, the third and fourth digits are the year (04 = 2004).

Hope this helps!

[Diplomat Don]

Kevin.....It appears that those are some pretty heavy duty tires for your rig. With your axle weights you're below the minimum pressure on the chart, of 80 psi. I would probably run them around 90-95 pounds to be safe and make the ride reasonably smooth.

[Mandys Man]

Quote:

Originally Posted by Diplomat Don Kevin.....It appears that those are some pretty heavy duty tires for your rig. With your axle weights you're below the minimum pressure on the chart, of 80 psi. I would probably run them around 90-95 pounds to be safe and make the ride reasonably smooth.

Here is the pressure table for RV tires
The earlier link is for trucks. I did not look, so I can't say if the info is the same or not.

Don, as usual is correct.
80 in the front just barely covers the axle weight you state. Normally I add 5 lbs for safety factor, but yours is so close I also would go to 90.
Same goes for the rear.

[namwob]

Thank you all... this helps a bunch. Yes, they are big tires. Apparently they were replaced as a recommendation by Monaco/Goodyear, which the previous owner did. The tires still have plenty of tread and sidewalls look good but they are at least 7 years old. Is there life expectancy that the tires should be replaced regardless of wear?
A little off topic but does anyone have an opinion of the use of Equal for balancing?

[Diplomat Don]

Mandys Man....I missed the fact that it was the truck chart. While sitting at work today......doing nothing lately.....I went to GoodYear's site. They don't show making a G391 tire anymore, but the numbering appears to be similar to their truck tire numbers.

The air pressure for the size that "namwob" has is the same in the RV tables too.

Kevin......The argument wages on about replacing tires after 7 years and I think it becomes more of a personal choice/financial issue. To replace all 6 is at least $3000.00 and another thousand if you have a tag. Lack of use is probably more detrimental to tire life than high mileage. If you blow a rear dual, it often causes a lot of damage. Sometimes you can replace the two front steer tires and then wait a year or so and replace the rears to help spread out the costs. You don't rotate this type tires so it's not crucial that you buy them all at once.

I worked at a tire store for the first three years of my working life. Since I'm REALLY anal/OCD I always spent time balancing tires perfectly, including rotating the tire on the rim to try and match the light spot of the tire with the heavy spot on the rim. Personally, I don't believe in balancing powders, beads or the mechanical type automatic balancers. I think a quality high speed spin balance can't be beat.

[Dr4Film]

Quote:

Originally Posted by Diplomat Don I worked at a tire store for the first three years of my working life. Since I'm REALLY anal/OCD I always spent time balancing tires perfectly, including rotating the tire on the rim to try and match the light spot of the tire with the heavy spot on the rim. Personally, I don't believe in balancing powders, beads or the mechanical type automatic balancers. I think a quality high speed spin balance can't be beat.

Diplomat Don, I totally agree with the high speed spin balance and it should be done while mounted on the coach to boot. I had my two front tires replaced awhile back and the shop did a static balance on them. The reason for replacement was the edges of both front tires had scalloped due to improper alignment from right out of the factory. The coach had only 42K on it when I purchased it from the original owners. They never took the time to correct the alignment problem. So when I took the coach in for the alignment, the service tech ask how the tires had been balanced. After telling him that they were static balanced, he suggested that before the alignment is done, that a spin balance should be done on each tire and they do that while the tire is mounted on the coach. It was an additional $50, but well worth it. The coach drives so much better than before and the tires will last a heck of a lot longer than 42K.

Dr4Film ----- Richard.

[namwob]

Do most shops offer dynamic balancing or does it require special equipment for coach?

[moisheh]

weathertodd: The pressure embossed on the side of a truck tire is NOT the recomended pressure. It is the maximum pressure necessary to obtain the maximum weight capacity of the tire. Think about it: How could they emboss the correct pressure on a tire wiothout knowing what vehcile is using that tire???

[Pairajays]

Just went through this with Michelin.

Here is my email to them.

Dale,

Thank you so much for your prompt response to my inquiry about air pressure in tires. With all due respect, I feel you gave me a boiler plate answer. I specifically asked what "cold means". Your answer implies cold means the temperature "at least three hours after the vehicle has been stopped and before it is driven more than one mile or two kilometers". So, if the vehicle tire placard states the pressure should be 100# that's what it should be after sitting for at least 3 hours no matter the ambient temperature. In the Southwest, daytime ambient temperatures can vary by as much 45° from daybreak to mid afternoon. So that means I would have to increase or decrease the pressure depending on the time of day I check the pressure.

I have seen charts that indicate 65° is a reference or "cold" temperature. If the vehicle placard indicates the cold tire pressure should be 100#, that pressure would be at 65°. If the actual temperature is something else, say 80°, then the pressure should be adjusted to something like 104#, but never less than the reference cold pressure. I'm not nit picking, 4 or 5 lbs. probably doesn't affect much anyway. Just trying to understand the physics or whatever of tires and pressure.

Another point, I believe the pressure listed on the vehicle tire placard is a CYA pressure, not the most desirable pressure for comfort, steering or longevity. If I weigh all four corners of my fully loaded MH, including fuel and water, then consulting the tire manufactures load charts would result in the desirable pressure. I would bet that at least 90% of the time the pressure would be less than MH tire placard specifies. I am aware the tire pressures on the same axle should be the same depending on the heaviest load.

I would really appreciate your comments.

Jim

Here is their reply.

Hi James,

You are correct the amount of air pressure you need to use depends on the
weight of your fully-loaded vehicle. As a result, it is impossible to
determine the correct air pressure unless you have the actual weight of the
vehicle fully loaded, by wheel position. You are also correct when you
stated that the tire pressures on the same axle should be the same depending
on the heaviest load.

Based on your information about inflation and ambient temperature
information, you have already reviewed the information from the RV guide
which is the same reference material we use.

If you have weighted your motor home and have the fully loaded weight then
you would use the chart for the minimum inflation needed to support that
weight. We suggested that you allow enough inflation for an additional 500
pounds reserve capacity not to exceed the max as branded on sidewall.

In you are using the vehicle in an extreme temperature we suggested the
inflation be checked based on the outside ambient temperature. You would
only need to adjust the inflation if you are checking inflation when the
vehicle is parked in a heated garage and the vehicle is going to be operated
in a very cold temperature.

Always check the tires when thy have not been drive more than one mile and
based on ambient outside temperature. The pressure in a hot tire may be
10-15 PSI higher then the cold pressure.(not driven over 1 mile).

If we are not answered your questions completely, we suggest that you
contact the nearest Michelin RV or Truck Tire Professional and have them
contact their Michelin Rep for assistance.

It is our goal to ensure that your issue has been resolved or your question
answered to your satisfaction. If we can assist you further, please respond
to this email or call us at 1-800-847-3435 (toll free) between 8:00AM and
5:00PM Eastern Time Monday through Friday.

Sincerely,
Colesta

Michelin North America
Consumer Care Department

[Dr4Film]

Quote:

Originally Posted by namwob Do most shops offer dynamic balancing or does it require special equipment for coach?

I don't think all shops will offer dynamic balancing. I went to a truck shop to have the alignment done only after having the tires replaced at a tire shop. The tire shop did a static balance (without asking what I wanted) and the truck shop did the dynamic balance while mounted on the coach, not on a separate machine similar to auto tire spin balance machines.

[William Willard]

I`ve owned 5 DP`s with 22.5 tires of different brands -- I put 100# in all tires, (except the tag, I put 90#) & have never had a tire failure or unusual tire wear except the Goodyear tires on the front, which almost everyone has experienced regardless of tire pressure -- I do put a lot of miles on coaches, almost 40,000 miles on our 07, 42' Camelot -- Tire pressure changes from day to day while traveling, so I see no need to worry to much about a few pounds of air -- Bill Willard