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Why Tag Tire Pressure Higher Than Duals?

Yahoo Message Number: 75975
The owners manual for the used 2003 Intrigue I purchased says the tire pressures were set at 120 front, 110 duals, and 120 tag. Why is the tag pressured higher than the duals?

Gary

2003 Intrigue #11509

Re: Why Tag Tire Pressure Higher Than Duals?

Reply #1 –
Yahoo Message Number: 75978
Gary This is the age old discussion about the Firestone/ Ford lawsuits over tire pressure , and the subsequent increasing of tire pressures to cover their butts. To summarize, it is generally agreed, that weighing your coach, and selecting the appropriate pressure for the tire , from the manufacturers tables ( why else would they publish the table ? ) is the recommended solution for proper tire pressures. FMCA is a proponent of this procedure. Plainly , disregard the pressure on the coach, as they are only any use if you were to sue CC. ( now not an option , as they were bankrupt ). On my 09 Magna , I was told by CC engineering, that they use the same pressures as Prevost bus. It makes no sense , as the weight distribution, is not at all comparable. ( a case of CYA ) .

Ron Baran 09 Magna 7025

Re: Why Tag Tire Pressure Higher Than Duals?

Reply #2 –
Yahoo Message Number: 75979
Quote
Quote from: Gary"
Gary,

Posted pressure vs. chart pressure is one question which has been answered but tag pressure is another issue. Do not use the charts for tag pressure! You may find that the weight on your tag tires is much lower than the individual tire (wheel) weights on the drive axle. If you follow the charts you will have very low psi on the tag and it may even be off the charts on the low end. Air your tag tires the same as your drive tires. Think dynamic load rather than static load. If you lose pressure in a drive tire the tag will have to take up the slack and too low pressure may also destroy the tag tire(s). Also, from time to time going over dips and valleys in the road the drive axle will be unloaded for a moment and the tag overloaded. (think speed bumps). So, once again you will want your tag aired up to handle the load. This is only my reasoning and I can't come up with a reason for the tags to be aired up to a pressure lower than the drive tires.
Lyle Wetherholt
04 Intrigue 11740
> The owners manual for the used 2003 Intrigue I purchased says the tire pressures were set at 120 front, 110 duals, and 120 tag. Why is the tag pressured higher than the duals? >

Gary

2003 Intrigue #11509

Re: Why Tag Tire Pressure Higher Than Duals?

Reply #3 –
Yahoo Message Number: 75981
To keep them from being damaged by scrubbing and other issues when people can't or won't lift the axle in turns, I surmise. Plus when you go over uneven ground they are taking on more than their share of weight from the duals. TWI 2004 Intrigue. 11731

Re: Why Tag Tire Pressure Higher Than Duals?

Reply #4 –
Yahoo Message Number: 75983
The uneven ground notion and that they could take on a high load at times seems to have some appeal as the answer.

Re: Why Tag Tire Pressure Higher Than Duals?

Reply #6 –
Yahoo Message Number: 75986
Read your tire sidewalls. Duals are never pressured to the same amount. At any rate, it is always specified by tire manufacturer.

Max

98 Affinity #5487

Re: Why Tag Tire Pressure Higher Than Duals?

Reply #7 –
Yahoo Message Number: 75991
To prevent duals from 1. rubbing together and 2. create more air space, dual tire configuration is always less pressure than single configuration.
Kent
SOB

CC wanna - be

Re: Why Tag Tire Pressure Higher Than Duals?

Reply #9 –
Yahoo Message Number: 75996
If you weigh your coach , as recommended by FMCA , you will see that the weight on the tag is usually a lot lower than the minimum pressure recommended by the tire manufacturers tables. I have weighed all my coaches and have never had either scrubbing or tire failure in over 150,000 miles ( combined between coaches ) If you follow the FMCA guidelines, you will get a better ride, and be well within the safety margins required by the tire manufacturer. The occasional time, where you put extra load on the tag, is not an issue as it usually is only momentary. If you want to pressure the tires, as per the label, it fundamentally rides like truck. However, each to their own.

Ron Baran 09 Magna 7025

Re: Why Tag Tire Pressure Higher Than Duals?

Reply #10 –
Yahoo Message Number: 75998
On my 2008 Allure the sticker says to run the tags at 85, the duals at 105 and the fronts at 120.. sounds different than what most of yours says..Bill

Re: Why Tag Tire Pressure Higher Than Duals?

Reply #11 –
Yahoo Message Number: 76000
Wow, hugely different than mine. Scratching my head even more now.

Re: Why Tag Tire Pressure Higher Than Duals?

Reply #12 –
Yahoo Message Number: 76001
okay. I run a fleet of trucks.... Here is what we do... 110 in steers 100 on all others. DO NOT run less than 100 in any tire, it will cause overheating, due to low pressure.

Mikee

Re: Why Tag Tire Pressure Higher Than Duals?

Reply #13 –
Yahoo Message Number: 76002
Well I run 315's on the front at 110, 295's on drive at 100 and tag at 85 with 50psi on the axle

Re: Why Tag Tire Pressure Higher Than Duals?

Reply #14 –
Yahoo Message Number: 76003
Mikee I can't believe you would bring truck tires into this discussion !! Truck tires are designed for trucks . The side walls are stiffer, and the loads vary greatly-- from am an empty tuck to a fully loaded one. Trucks towing trailers, are capable of moving the rear axle of the trailer to get the weight evenly distributed on all the tires and axles. RV tires are made for RV's and RV's only. The carrying capacity of my coach varies by only about 3000 to 4000 pounds, on about 50,000 pounds base . The side walls on RV tires are built to give a softer ride. This is exactly why FMCA encourages that your coach be weighed, to get the proper inflation for a specific coach. I would bet that , all those who have responded about their pressure differences , have never had their coaches weighed. There is only ONE way to get the proper tire pressure, and that is to weigh your coach, with it's typical loading. You would then see how close you are to the weigh limits, for each axle. If you are over for an axle allowable weight, you have to re-distribute your weight. Many , many coaches are overloaded, because they never have been weighed. Once the weight has been established , ALL manufactures , provide tables to determine the appropriate tire pressure. There is NO other need for the manufacturers to provide a table , if you inflate it , to near it's maximum. I guess, as I said before, if you want it to ride like a truck, then put tire pressures the way truckers do.

Ron Baran 09 Magna 7025

Re: Why Tag Tire Pressure Higher Than Duals?

Reply #15 –
Yahoo Message Number: 76006
I received an email recommending 6 point weighing. I understand I really do need a good weighing. But it would seem to me that if I do one of the weighs with only a tag tire it will weigh a lot more than if all 3 tires of that corner were on the ground and I would inflate the tag far more than needed?
So far, I have reviewed the four point weighing of the factory (they didn't provide a six point) and I have estimated the additional load I have put on each corner. I used the Bridgestone inflation guidelines (I put 12R22.5 R250F's on it). I inflated the fronts as recommended in the table plus I added a 5 pound saftey margin. For the rears, I inflated the duals per the table without considering that there is a tag tire back there, again with a 5 pound safety margin. Then I inflated the tag with 10 pounds more than the duals as that is what they did at the factory. The result is 115 front 105 duals and 115 tag. If anything, I figure I am a bit high in the rear, but the values don't seem unreasonable.
But still not convinced I know why CC would have 10 pounds more in the tag than in the duals. Maybe I will give Bob Dickman Les Schwab in Junction City a call.

Re: Why Tag Tire Pressure ....WEIGH YOUR COACH FIRST, then comment h

Reply #16 –
Yahoo Message Number: 76007
This discussion/argument has been posted at least 20 different times over the years on this site. It amazes me that no one even bothers to check prior posts before bringing up this topic again.
I think there are at least four topics that seem to light up the boards; tires, batteries, tag axels and refrigerators.
That said, the answer to the tire pressure question has to first start with weighing you coach like Ron Baran below has said. Read his message. It is spot on. If you want go by the placard next to your driver's seat then you are just following what the manufactures CYA and assume that you are running maximum loads on each axel. Why would the manufacture say anything less? For liability reasons? If you want to have the most comfortable ride then maybe you can get away with less air in tire and at the same time be doing what the tire manufacture suggest you should be doing.
For those of you who have no idea if your coach is over loaded then you are running a higher risk than those that match their tires pressure to what the tire manufacturer suggests. There must be a good reason why tire manufactures make different tires for different types of vehicles as Ron suggested in his comments below. I will assume they know more than me about that topic and will not second guess them like some of you do.
GET YOUR RV WIEGHED AT WHAT EVER NORMAL LOAD YOU TRAVEL WITH! That is the only sensible thing to do before posted another post asking or telling a bunch of RV owners on this site what they should do. It just confuses some of us more. Even the Les Schwab store in Junction City told me the same thing after they put my tires at 120 in the front, 110 on the drives and 120 on the tag. They inflated them to the placards recommendations for liability reasons but suggested that my ride would be allot better if I did it to the manufactures specs once I got it weight.
I weight my coach quite often now. There is always an off hour closed weight station on the side of the highway that leaves its scale on when they are not open. Use them. ITS FREE! I did again just last week and found out that one of my tag airbags is inflating more than the other side because the weight difference between the left side and right side was quite different (> 1500lbs),... next project.
When you use one of the hiway truck scales, run the coach half off the weight scale on each axle and then on both wheels on each axel, do some simple math to get the weight on every axel and inflate the tires on each axel to the proper weight based on the heaviest side for each axel when the tires are NOT at hiway temps of coarse.
My Michelins now run 110 on the front, 105 on the drives and 110 on tags with a 37,840 lbs coach that would be fully loaded at 44,200 GVWR according to the Manufacture Country Coach. I have temperature and pressure gauges on each tire that report and so far I have found my ride to be more comfortable using Michelins recommended pressures than running the max pressure as suggested by CC, with no unusual tire wear or temperature patterns in the last 10,000 miles this past year.
THIS INFORMATION IS JUST FOR MY COACH and should not be construed to be for any other coach similar to mine. I am not telling anyone to use my tire pressures. As for why the tag has more pressure than the drive axel. Simple. The drive axel is dispersing wieght across four tires and the tag across two. The tire manufacture explicitly states what the pressure sould be according the the wieght each tire supports and that means the tag as more weight on that axel than the dirve axel. For those of you who think differently then read the tables. I found no other logic besides what CC and the tire manufacture both confirm. I don't have to be very smart to understand this concept.
For those worried that blowing a drive tire will cause the other to blow immediately, I suppose that could happen if you ignore it for too long. But I would certainly pull over and maybe inflate the other one a bit up till I got to safe place to change it. In the mean time I would enjoy the improved ride till till that happens.
Get you coach weighed first, then use the internet to find the table for your tires from the manufacture and you won't need to get bad advice from others who have not weighted their coach but feel that they know more than the tire manufacture does.

Read Ron's post below. It is spot on in my opinion.

Dallas 2004 intrigue ovation C12 11688

Re: Why Tag Tire Pressure ....WEIGH YOUR COACH FIRST, then comment h

Reply #17 –
Yahoo Message Number: 76011
I did a search before I posted this topic and didn't quickly find the question I posted.
You wrote "As for why the tag has more pressure than the drive axel. Simple. The drive axel is dispersing wieght across four tires and the tag across two. The tire manufacture explicitly states what the pressure sould be according the the wieght each tire supports and that means the tag as more weight on that axel than the dirve axel."
Since posting my topic, I have been learning and thereby doing more research. It seems the answer may be how much the tags are pressured to the road by the air spring vis a vis the air spring pressure on the duals and therefore how much total weight each rear area tire is carrying. The more air spring pressure on the tag, the more weight it carries and the more air pressure the tag tire needs. The less air spring pressure on the tag, the less weight it carries and the less tire air pressure it requires.

Others, is that correct?

Re: Why Tag Tire Pressure ....WEIGH YOUR COACH FIRST, then comment h

Reply #18 –
Yahoo Message Number: 76012
Dallas AMEN !!!! Thank You

Ron Baran 09 Magna 7025
 

Re: Why Tag Tire Pressure ....WEIGH YOUR COACH FIRST, then comment h

Reply #19 –
Yahoo Message Number: 76016
I'M GUILTY OF NOT SEARCHING! It was because I was new to doing any board memberships at all, and frankly was just not aware of all of the great info that can be found by searching.
So, I always remember how nice people were to me, as I asked for the 3,431 time about Dino vs Syn, or on HiFi boards Tubes vs SS:)! I had a very nice private PM from a board member (Wolfe over on RV.Net, you know, the gent with the great Foretravel, and who knows a few things about Cat's:)!) - about how to use the search. (And yes, I had some flames tossed to me on the posting by other too...)
I will also comment, that as much as I enjoy the membership and info on this board - the search, and advance search, are far from being very slick... So, sometimes search will not result in what you looking for. (PTO was that way for me. I read ALL of the search items, looked at the links and the database too - but found nothing to back up the Cummins shop telling me my ISL did not have a PTO... Thus a post to this board for input about this subject.)
Will search provide most answers related to tires, tire PSI, tag's vs non tags? Yes it will... But, I will do my best to answer if I think I know. Oh, and I too now do PM's to let people know about search features.
Dallas - Not a slam to you at all, and I understand your comment was meant to inform that other history info was available - and as always, you did continue on in your post with your info sharing, as you always do.
I just wanted to remind us all - that we all were once new to all of this...

Best to all,
Smitty

04 Allure 31017
04 Allure Sold to a nice new owner! Now enjoying a 07 Magna Rembrandt 45' ISX600 #6775
"We're ONDROAD for THEJRNY!" (Toad and Coach license plates, say Hi if you see us!)