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Old 12-02-2012, 09:13 PM   #29
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Tireman - I need 6 new tires for my 2001 Georgie Boy Cruise Master - my Goodyear 245/70R 19.5 were all built in 2000 and look great with lots of tread left but.... here's my confusion: I can buy 12, 14 or 16 ply tires - there is a considerable price diff from 12 to 16 ... could I get by with 12 ply or should I just split the diff and go for 14 ply... ??? Thanks for clearing some confusion!!
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Old 12-03-2012, 11:02 AM   #30
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What Load Range to buy

denforent,
Sorry to answer your question with a question but before I can answer I need to know what the actual load on each corner of your RV is when the RV is fully loaded.
I numerous threads on this and other forums as well as on my blog RVTiresafety dot com the topic of what inflation you need has been covered a number of times but to cover it briefly.
1. To know the Load Range (ply rating) for the size tire we need to know the max cold inflation needed for the load.
2. To know the inflation needed we need to consult Load/Inflation tables and look up the load.
3. To look up the load we need to know the actual load on the tires.

Your actual load is not simply the axle load divided by two as the side to side balance is almost never 50/50 and your front/real weight split is never 50/50. Here is an example from a thread here on iRV2
TYPE Class-A
RF - 4650#
LF - 4950#
RR - 9050#
LR - 7800#

In this example the owner would need enough air to carry 4950 on the fronts and 9050 on the rear duals.
If you need help in calculating the four corner loads you can find more info and even a worksheet HERE.

Once you have the weight numbers then I would be happy to provide advice on what inflation you really need and which Load Range you need for your specific coach.
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Old 01-14-2014, 09:44 AM   #31
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I'm heading out tomorrow to get my new rear tires, got 2 new Michelin 275/70 R22.5 XRA2's for the front a month or so ago, now getting the
same for the rear with the long valve stems so I can gauge the inside ones.

I'm going to have them put 100 psi all around, I did 95 or so in the front and not sure its enough, not steering as well as the 2 old mismatched ones.

I'm heading out Thursday or Friday and going to stop at a truck stop and get weighed so I can have the pressures adjusted according to Michelin's psi and weight chart.

Sounds silly to get excited over tires, but we don't know the age of the
inside dualies and the outer ones are 10 years old with a bit of surface cracking. To old in my book to trust on a several miles trip. And for what they cost, I need to get excited, most expensive thing I've bought lately.
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Old 01-15-2014, 11:07 AM   #32
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Originally Posted by PatStab View Post
I'm heading out tomorrow to get my new rear tires, got 2 new Michelin 275/70 R22.5 XRA2's for the front a month or so ago, now getting the
same for the rear with the long valve stems so I can gauge the inside ones.

I'm going to have them put 100 psi all around, I did 95 or so in the front and not sure its enough, not steering as well as the 2 old mismatched ones.

I'm heading out Thursday or Friday and going to stop at a truck stop and get weighed so I can have the pressures adjusted according to Michelin's psi and weight chart.

Sounds silly to get excited over tires, but we don't know the age of the
inside dualies and the outer ones are 10 years old with a bit of surface cracking. To old in my book to trust on a several miles trip. And for what they cost, I need to get excited, most expensive thing I've bought lately.
Glad you are replacing the old tires. Even if you can't get the individual tire loads (ie corner weights) of your loaded RV you can still do a quick run across a CAT scale and confirm your axle loads. With that number you consult the Load/Inflation tables to establish the MINIMUM cold inflation. It is suggested you add 5 to 10% as a safety margin and use that number when checking cold inflation.
Do you have a TPMS? It might just save the cost of a tire if you get a puncture or slow valve leak.
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Old 01-15-2014, 11:28 PM   #33
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No my motorhome is old and I haven't had them on any motorhome I've had.

I understand they are nice to have and may later down the road. One reason I got the XRA is they are supposed to have a more substantial sidewall to help them not get punctured or cut so easily. The motorhome did have them on the ones we could see and one Goodyear. I asked the tire store guy how old the inside ones were, just out of curiosity but he didn't really want to answer me so I didn't find out. They didn't have the long stems in, showed me the ones the fire department uses, well those don't help me, I can't get to them. He got some long ones but said if they are any longer they tend to leak. I had braided ones and they are worthless but then we got the long steel ones for the last motorhome and they did well. They went to a big truck place and got them so hoping they are good. I hate fighting to try to get a pressure on those inside dualies now I don't have to IF they don't leak.

Yes I will hit a cat scales and at least get the front axle and the back one weighed separately. I'm not sure I can load water, think it might be to cold, not that it will freeze I have heated bays but that I can't stand the cold to put it in, brrrr. Supposed to be 24 Friday, the oil will be thick that morning. It didn't want to stay running yesterday morning and I found my batteries were way down on their charge, hooked up my battery minder overnight and she kicked right off and kept running this morning and I started out slowly.
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Old 01-20-2014, 10:18 AM   #34
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Have to wonder why the tire guy didn't want to tell you the tire age. Maybe he knows that they are old.
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Old 04-23-2014, 10:42 PM   #35
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(Okay..just not sure where to post this, feel free to move to proper place)

Tires: Yup, yet another post, but I do need some help here.

I have a 1997 Rexhall Air 32' Class A MH and am about to pull the trigger on tires.
I have been so concerned about making sure I get the 'right' tires, meaning, ones that have the right load range and capacity.

So just today I FINALLY found a place to weigh the MH and here's what I have:
Actual Weight Sticker Info
Front Axle 4960 6000
Rear Axle 10660 11000
Total 15620 17000

I was concerned that the 235/85R16-E 10 ply load range of 3042 was too close to the limit so instead of I was thinking of getting a G 14 ply rated tire.

But now that I see the actual weight should I stick with the E - 10 ply range?

Here's additional info: The RV had 3/4 tank of gas, full tank of clean water, very little in gray water and me (175 lbs)

And is this how you figure "Reserve Capacity"?

Tire rating for 235/85R16 Load Range E = 3042
So is the reserve load range capacity minus actual weight?

(Dang! This looks good when I edit it, but after I post it's all over the place..sigh)

Front Capacity 3042 x 2 6084
Rear Capacity 3042 x 4 12168
Front Axle Weight 4960
Rear Axle Weight 10660
Front Reserve 6084 - 4960 1124 - I can add this much weight to the front
Rear Reserve 12168 - 10660 1508 - and this much to the back

Compare to Hercules H-901 Load Range G = 3756 (3415 Dual..why?)
Front Capacity 3756 x 2 7512
Rear Capacity 3415 x 4 13660
Front Reserve 7512-4960 = 2552 *Much better compared to 1124 lbs
Rear Reserve 13660-10660 = 3000 *Much better compared to 1508 lbs

So, gosh...now that I have actually put it all down on paper it's kind of a 'duh' moment, but here's the price difference:

6 - Cooper A/T3 - 1159.00 Out the door
6 - Hercules H-901 - 1532.00 OTD
Difference 373.00

Worth it?
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Old 04-24-2014, 10:04 AM   #36
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Quote:
Originally Posted by TriMoot View Post
(Okay..just not sure where to post this, feel free to move to proper place)

Tires: Yup, yet another post, but I do need some help here.

I have a 1997 Rexhall Air 32' Class A MH and am about to pull the trigger on tires.
I have been so concerned about making sure I get the 'right' tires, meaning, ones that have the right load range and capacity.

So just today I FINALLY found a place to weigh the MH and here's what I have:
Actual Weight Sticker Info
Front Axle 4960 6000
Rear Axle 10660 11000
Total 15620 17000

I was concerned that the 235/85R16-E 10 ply load range of 3042 was too close to the limit so instead of I was thinking of getting a G 14 ply rated tire.

But now that I see the actual weight should I stick with the E - 10 ply range?

Here's additional info: The RV had 3/4 tank of gas, full tank of clean water, very little in gray water and me (175 lbs)

And is this how you figure "Reserve Capacity"?

Tire rating for 235/85R16 Load Range E = 3042
So is the reserve load range capacity minus actual weight?

(Dang! This looks good when I edit it, but after I post it's all over the place..sigh)

Front Capacity 3042 x 2 6084
Rear Capacity 3042 x 4 12168
Front Axle Weight 4960
Rear Axle Weight 10660
Front Reserve 6084 - 4960 1124 - I can add this much weight to the front
Rear Reserve 12168 - 10660 1508 - and this much to the back

Compare to Hercules H-901 Load Range G = 3756 (3415 Dual..why?)
Front Capacity 3756 x 2 7512
Rear Capacity 3415 x 4 13660
Front Reserve 7512-4960 = 2552 *Much better compared to 1124 lbs
Rear Reserve 13660-10660 = 3000 *Much better compared to 1508 lbs

So, gosh...now that I have actually put it all down on paper it's kind of a 'duh' moment, but here's the price difference:

6 - Cooper A/T3 - 1159.00 Out the door
6 - Hercules H-901 - 1532.00 OTD
Difference 373.00

Worth it?

Some comments and observations.

It helps if you use the complete tire type/size nomenclature.
I believe you have LT235/85R16 LR-E the LT is Type. Some readers may have a trailer and have ST type tires and there are full metric tires with no leading letters. Each type has different load capabilities and ST are not intended for passenger carrying vehicles.


Second you failed to consider the correct load capacity in the dual position as your rear tires are. Tires in dual application ALWAYS have a lower rating than when in single as one of the pair is ALWAYS carrying more than 1/2 the load of the pair.
When you either read the tire sidewall or look at Load/Inflation charts you will see a different load capability for Single (as in your front tire) or Dual (two tires side to side as in your rear.

The load capacity for an LT235/85R16 LR-E in Dual application
is probably 2778#. Note you should always consult the Load/Inflation tables or molded on the sidewall from the tire manufacturer of the tires you are considering as not all tires have the same load numbers. Some are slightly different for a variety of reasons.

So back to your questions.

"Reserve Capacity" would be the (max tire capability) - (the actual load) on a tire.
BUT you cannot simply assume the load on an axle is split 50/50 side to side.
Some owners find significant variation so untl you learn the individual tire loads I suggest you assume that one side is carrying 55% of the axle load.

Your heavy side Front could have 55% OF 4960 OR 2728#
Rear 55% of 10660 or 5963#

Your front Reserve is 3042- 2728 or 314# per tire

Your rear would be 1/2 of 5963 or 2982
so the rear reserve is 2778 - 2982 or a negative reserve or potential tire overload of 204# per tire.

With this information it is important that you first confirm the side to side load balance

Here is a worksheet

After confirming the real side to side split you need to re-calculate your reserve load and if needed unload or shift the load of stuff in the RV or buy the tires with more load capability BUT you should never exceed the individual axle ratings GAWR or Vehicle rating GVWR shown on your certification label.

Hope this helps
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Old 09-22-2014, 09:55 PM   #37
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Newbie here. I've read the threads and need some help deciphering the load guides and determining tire pressures for my 40' DP. I've read about how to weigh my coach and have done so on a scale that will weigh each axle and provide the total.

My coach has a
GVWR of 32,000lbs
GAWR Front of 12,000lbs (6,000lbs per tire assuming equal weight?)
GAWR Rear (Dual but no tag) 20,000lbs (5,000lbs per tire assuming equal weight?)

I weighed it with full fuel, Propane, wife, me, 1/3 tank fresh water
Front : 10,260lbs
Rear: 18,720lbs.

I realize I'll need to weigh it again with a full load, but for purposes of this explanation,,, and making the ASSumption that the weight is equally distributed left to right, do I simply divide the

front weight by 2 10,260lbs / 2 = 5,130lbs
Rear Weight by 4 18,720lbs / 4 = 4,680lbs

and refer to the chart using the Single weight/PSI value for the front and use the Dual weight/PSI value for the rear?

Goodyear S670 275/80R22.5 H load rating

S 5,500lbs 90psi (use this on front tires since it is the minimum pressure?)
D 5,080lbs 90PSI (use this on each of the four rear tires since it is minimum pressure?)

Additional tire pressures below:

S 5,745lbs 95psI
D 5,305lbs 95PSI

S 5,985lbs 100PSI
D 5,530lbs 100PSI

S 6,225lbs 105PSI
D 5,750lbs 105PSI


Thanks!
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Old 12-18-2014, 02:25 PM   #38
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Inflation for tires

I know how important it is for proper tire inflation. I have had 10 different types of RV's. But with dual rear tires ---just try and find a gas station or ??? that will have the proper fitting on the air hose. I know you can install adapters that will turn the salve stems so that a normal air hose will work---I had it done on my 37' Itasca. But one side developed a slow leak. So it required checking more often. Any Ideas?
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Old 12-19-2014, 11:22 AM   #39
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I know how important it is for proper tire inflation. I have had 10 different types of RV's. But with dual rear tires ---just try and find a gas station or ??? that will have the proper fitting on the air hose. I know you can install adapters that will turn the salve stems so that a normal air hose will work---I had it done on my 37' Itasca. But one side developed a slow leak. So it required checking more often. Any Ideas?
With your "Fleet" of vehicles you probably need your own source of high air pressure with an appropriate air chuck.
It sounds like you need to modify your tire valve situation with appropriate long stem truck valves. You also need your air hose to have a dual foot air chuck end.
A bit of advice of checking and adding air to tires. Unless you have a short straight stem you should not just press a long air chuck onto the valve as this can put side force of the rubber gasket where the stem mounts to the wheel. this side force will "rock" the stem back & forth which can weaken the joint.
Long truck stems are available that can be bent if needed. I have no idea what your various wheels might look like or the size of the "hand holes" you have that allow access to the inner dual.
The short stem on the inner wheel needs to be oriented to allow access through the hand hole. The outer dual short stem is pointed to the inside so the reverse foot on the dual foot air chuck would be used then.
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Old 02-17-2015, 10:36 PM   #40
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Looking for tire recommendation. I have Michelin G670 RV size 275 80R 22.5 Load rating H tires on my National Pacifica 40' DP.

I'm a member of FMCA so I am looking at the Michelin XZA3, XZE, XZE 2. Any particular recommendations?

Also I'm looking at getting a TPMS and am looking for recommendations?

Thanks
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Old 02-18-2015, 10:41 AM   #41
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Quote:
Originally Posted by jstdreamin View Post
Looking for tire recommendation. I have Michelin G670 RV size 275 80R 22.5 Load rating H tires on my National Pacifica 40' DP.

I'm a member of FMCA so I am looking at the Michelin XZA3, XZE, XZE 2. Any particular recommendations?

Also I'm looking at getting a TPMS and am looking for recommendations?

Thanks
TPMS: I have 20 posts on the subject. on my blog. Did you read them? or even the one "Best TPMS"?
I bought TireTraker myself.


Tires: you said you have Michelin G670 ! I suggest you take another look at your tires.
You might also read the FMCA forum on tires.
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Old 02-18-2015, 10:33 PM   #42
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Strange......I have Goodyear G670 RV on mine. Sorry, I couldn't resist it.
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