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Old 04-10-2016, 10:36 AM   #1
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2002 CC Affinity B&B 42' with Tag Tire Pressure

We just purchased this Affinity and are currently near Kansas City, MO. While driving in some wind the coach was all over the road, riding rough. I stopped at a rest area to check tire pressures and discovered the front tires were set at 145 lbs warm or hot. I let air out down to 135. This morning, the front tires are 125 cold. If I'm reading the Toyo's pressure chart correctly, front axle of 14,900 divided by 2 is roughly 7500. Chart says single axel says pressure of 105. Am I reading this right?

I am new at this but 135 or 145lbs seems terribly high. Went to a Cat scale last night and had it weighed. Full of fuel and water, no toad. PO said tag was set at 35lbs. Couldn't do a four corner but this is what we got for weights.
Front-14,900
Drive-18,920
Trailer-8,540
Total-42,360

Tires are new Toyo's M144
Front 315/80R 22.5 M170
All rears 12R 22.5

I could really use some help with reasonably close tire pressures.
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Old 04-10-2016, 12:15 PM   #2
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If you have the 9 inch. rim according to Michelin you could set your front tires 115PSI cold. If a 8 1/4 rim you would need to raise 120PSI. It is best to get each tire weight separate since many coaches have over 500 and even 1000 lbs difference on each axle. Then you would have to double the weigh of the heavy side to use for your axle weigh.
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Old 04-10-2016, 12:23 PM   #3
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May have too much down pressure on tag, transferring weight to front end.
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Old 04-10-2016, 02:05 PM   #4
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Welcome, Barney. We have the exact same coach. B Bob has one too.

This sticker should be on the panel to the left of the driver's seat below the switches, mirror adjust, transmission shift pad, etc.



Your tire sizes are the same as mine though we have Toyo M170's on the drive and tag with Firestone FS400's on the steer. Nevertheless, here's what we run in terms of tire inflation pressure.

Steer: 120 PSI
Drive: 105 PSI
Tag: 115 PSI

Here's a link to the Toyo webpage for your M144's.

Toyo M144 Web Page

They don't make it easy to get to the heavy truck tire info but once you get to the M144 page click on the menu icon in the upper right corner that looks like 3 short horizontal bars. On the pop-up window that appears look for "Application & Technical Data" and you will get more than you wanted to know. That will have the M170's too.

BTW: "Trailer" in this context means trailer as in "tractor/trailer". Mostly folks refer to our axles as steer, drive, and tag.

HTH
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Old 04-11-2016, 06:30 AM   #5
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Advice made with use of my made motorhome tirepressure calculator.

Used the GAWR's given by CoCoDave and Barney's given weighed axle loads.

Advice given for :

weight and reserve/Front/Drive/TAG

GAWR+0%/125psi/87psi/88psi
GAWR+Fr5% D+Tag 10%/132psi/96psi/97psi
Weighed axles+10%/117 psi/91 psi / 74psi = minimum for 75m/120km/h
Maximum for weighed axle loads + 10% without bumping/133psi/93psi/84psi

The 10% adding to loads is absolutely needed to cover unequall loading R/L . for motorhomes a 48/52% loadivision per axle is pretty common, 45/55% is also seen sometimes.
But also for things like pressure loss in time, misreadings of pressure- and weight-scales, etc. can be that you calculate for maximum reserve, but because of all the inacuracies you only yust have enauch to prevent damage to tire.

But better would be to highen up the 35psi pressure on tagaxle so Tag and front axle get more load on them and drive axle becomes lower load.
Then you should re- weigh again fully loaded as you go on trip, as I assumed you weighed first, and I then can recalculate for you.
This would give probably less nervous stering, and better comfort.

If you would lift up your tag ( if possible) , for instance to prefent you from turning the stones of a drive way when curving, the total weight of 42,320 lbs comes on rear and front axle, probably lower load on front and mayby even 30000 lbs on drive axle.
Because then verry low speed, the tires still wont get damaged on drive axle, even with the lower pressure for weighed loads calculated.

This is the short version of my post, first longer one got lost when submitted, because I first had to log in again and screen stayed blank.
Because of that now first copied the text , so I wont loose it again.

Greatings from a Dutch Pigheaded Selfdeclared Tirepressure-specialist.
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Old 04-11-2016, 07:35 AM   #6
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Quote:
Originally Posted by stuhly View Post
May have too much down pressure on tag, transferring weight to front end.
In my post before this one you see that even pressure needs to be highened up, to give more weight on front and tag and lesser on drive axle.
This would bring the weight on front closer to the loadcapacity for the pressure topicstarter is using.

Also tag is not using its GAWR fully so can also have more weight
Drive axle is close to its max so a little lower is better.
This all makes the weight more devided between the axles , wich probably gives better handling.

to make it complete , the advice pressures are cold measured, so when inside tire temp = outside tire temp and about 18-20 degr C/65-68degr F

So must be measured when not driven for a while ( hours) and no sunshine on tire.
So the 145 pressure warm measured by topicstarter, was cold probably less then 10% lower but unpredictible , because can also be after severe braking , then heat of brakes is transfered to the tire inside by the rimms.
But he measured cold afterward a pressure of 125 psi nice in between 117 psi lowest and 133 psi highest border .

this all make me suspect the discomfort not to be because of to high tirepressure , but the deviding of weight between the axles.
For that reason I advice to play with the pressure of the tag axle ( that 35 psi)
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Old 04-11-2016, 08:40 AM   #7
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Barney, whatever you do, don't ever let the tire pressure exceed that pressure listed on the sidewall of the tire. 315/80s have a max pressure of 130psi when cold.
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Old 04-11-2016, 09:19 PM   #8
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Quote:
Originally Posted by Peralko View Post
Barney, whatever you do, don't ever let the tire pressure exceed that pressure listed on the sidewall of the tire. 315/80s have a max pressure of 130psi when cold.
Thank you all for your responses and opinions. This forum is a wealth of information to the new folks plunging in like us.

This morning before I was able to read some of your responses I was sitting at a Pilot truck stop who had a full tire shop on site. I walked in and discussed the tire pressures with the guys on duty. They are not RV experts and they admitted that but after looking at the axle weights in my first post, we came to more reasonable pressures. Not spot on but way better. Instead of a white knuckle terror ride, it's now very predictable and well behaving. I just need to get it properly dialed in.

The thing is I'm reluctant to blame this on the seller who is very knowledgable about Country Coaches in particular but I when the new Toyo's were put on just before selling the coach to me apparently didn't check pressures. Neither did a well known and respected Country Coach service facility who did some repairs before I left Oregon. I should have double checked, lesson learned.

Anyway, the tire techs looked at the axle weights and after looking at the Toyo's pressure charts we decided on 110lbs on the front, 110lbs on the drive and 100lbs on the tag for now. These pressures are not spot on but the drivability improvement is remarkable.

The front pressure was fairly easy, the drive and tag pressures shown on the Toyo chart don't seem to make sense unless the tag weight is off. I really don't know the correct term for describing this but it seems to me the drive axle is near maxed out and the tag is underweighted. If my tag was adjusted to bear more weight the weight/pressure numbers would make more sense. For instance, taking the tag weight of 8,540lbs and dividing by 2 to get the weight per tire is way below where the Toyo chart starts.

Am I on the right track?
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Old 04-11-2016, 11:10 PM   #9
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BarneyR - CoCo Dave and I have exactly the same coach as you. His recommendations are pretty good. I have a factory recommended settings card to the left of the drivers seat. You should too. When I have taken mine to the CC factory in Junction City that is what the put in. I have to say the best handling has been when my coach was the 130,110,120. But much of the time my pressures are not at those levels. My handling gets sloppy when the fronts get too low, around 100.

You are lucky the rims did not fly apart on you. Your fronts are rated max cold of 130. You were way over that. The other rims are 120's. You can tell by small holes. The small hole rims are 130's. There are lots of "slide rule" people on this web site that will spend a lot of time calculating the ideal pressure and so on. For me the best pressure has been about 120 in the front, 110 in the drive tires, and 115 in the tags.

You have new Toyos. These coaches came with Toyos new. I know there was some sort of problem and law suits back when these coaches were near new. I don't know what was the problem. But I am aware of it and I have stayed away from Toyos because of it. Seems like 4-5 years ago If you checked Toyo tires there was some kind of legal words on their web site saying not to put their tires on Country Coaches. But other people will have to provide the information on that.

I am not surprised your rig was riding rough and all over the road with the pressure you were running. Your front end must have been like a pogo stick.

If you need other information on the coach I am glad to oblige. We have had ours since 2009 and very happy with it.
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Old 04-11-2016, 11:29 PM   #10
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Didn't you say you checked your tires at a rest stop warm/hot after driving and they were 145 warm ? and lowered them ??? Tires gain pressure after driving. a a cold 120 psi tire could go to 145 easy. I never adjust tires warm. (driven) only after sitting hours or overnight. Tires and wheels are rated for their un-driven "cold" pressure not the hot. on my tpms my fronts are easily 130-140 after a short 10mile drive on a warm day.
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Old 04-12-2016, 12:01 AM   #11
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CC has changed their "rules" on tire pressure for the later rigs. Here's what ours says:
Quote:
Tire Industry Changes
The tire industry, as a whole, has changed its traditional stance on adjusting cold tire inflation pressure for RV tires installed on recreational vehicles and busses. Previously, tire manufacturers supported a policy where tire inflation could be adjusted according to the actual loaded weight of the vehicle. Now, the major tire manufacturers recommend that medium duty truck tires be maintained at the pressure that corresponds to the Gross Axle Weight Rating for the axle to which they are mounted. To make this recommendation uniform across the industry, tire manufacturers strongly urge the consumer to keep all tires inflated to the pressures recorded on the Federal Tire Label.

Tire Inflation
Country Coach recommends that the cold tire inflation pressures should at all times be maintained at the inflation pressure(s) recorded on the Federal Tire Label. There are no acceptable circumstances where tire inflation pressure(s) should be reduced below that pressure recorded on the Federal Tire Label.
Now, do I follow that? NO!!
I'd need 125 front
105 drive
105 tag
Here's my sticker:
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Old 04-12-2016, 05:50 PM   #12
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I have found the sticker, same as CoCoDaves. I'm especially concerned about actual drive and tag weights as compared with this sticker/plate.

My actual drive weight is 18,900 compared to 20,000 max weight
My actual tag weight is 8,540 as compared to 14,000 max weight

Could someone tell me their Affinity Drive and Tag weights so I can get a better idea if my tag is "light". It seems to me that until the weights are balanced on the drive/tag I can't set an accurate tire pressure.
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Old 04-12-2016, 08:08 PM   #13
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Quote:
Originally Posted by BarneyRubble View Post
I have found the sticker, same as CoCoDaves. I'm especially concerned about actual drive and tag weights as compared with this sticker/plate.

My actual drive weight is 18,900 compared to 20,000 max weight
My actual tag weight is 8,540 as compared to 14,000 max weight

Could someone tell me their Affinity Drive and Tag weights so I can get a better idea if my tag is "light". It seems to me that until the weights are balanced on the drive/tag I can't set an accurate tire pressure.
Your misunderstanding the Tag ....To me your weights look fine ! Whats wrong ? With just the coach. no trailer etc the tag will never have close to 14000 on it!!! the more you increase the tag weight , by adding down pressure to the tag suspension you un- weight the drive axle but ADD weight to the front. The tag is there to handle the harleys on the bike rack :-) and the 10,000 lp trailers 1000 lb hitch weight. 8540 is fine .. at least on my 41' tag .. not a cc but still a very heavy coach. Mine has about 7000 on it and its fine Forget about trying to run up the tag weight . Its not supposed to be "balanced" with the drive axle :-(.! Make sure the front and drive are under limits is all. you can use the tag to add or take weight off the front.
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Old 04-13-2016, 11:48 AM   #14
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Quote:
Originally Posted by BarneyRubble View Post
Could someone tell me their Affinity Drive and Tag weights so I can get a better idea if my tag is "light". It seems to me that until the weights are balanced on the drive/tag I can't set an accurate tire pressure.
Here are my weights.

Steer Axle - 14,240
Drive Axle - 17,700
Tag Axle - 8,420
================
Total - 40,360

This is with the fuel tank full and other tanks (water & holding) empty.

With a GVWR of 48,500 I'm perfectly comfortable with the proposition that even my DW will not come up with over 8,000 pounds of luggage. Yes, I acknowledge that my inflation pressures are slightly reduced thus lowering the gross weight supportable by the tires. Even so there is little chance that we would equal or exceed the payload dictated by the actual tire inflation pressures.

FWIW
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