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Old 04-18-2015, 05:01 PM   #141
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You need to meet the tire capacity and the individual axle capacity GAWR and the vehicle capacity GVWR.

To get increased load with the 275/70R22.5 you need to go up in inflation. What are your wheels rated for. Not all 22.5 wheels are rated for 130 psi.

Assuming your readings represent your MAX tire load you need at least 6280 assuming you are willing to ignore the fact you are over-weigh on GVWR.

According to Michelin tire load tables, you need at least 115 psi with zero margin so 120 might be reasonable.

I think you need to do a review of the "stuff" in the Rv when actually loaded as you travel and you should be at tire and axle and vehicle max ratings or lower.
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Old 04-19-2015, 10:19 AM   #142
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Originally Posted by Tireman9 View Post
You need to meet the tire capacity and the individual axle capacity GAWR and the vehicle capacity GVWR.

To get increased load with the 275/70R22.5 you need to go up in inflation. What are your wheels rated for. Not all 22.5 wheels are rated for 130 psi.

Assuming your readings represent your MAX tire load you need at least 6280 assuming you are willing to ignore the fact you are over-weigh on GVWR.

According to Michelin tire load tables, you need at least 115 psi with zero margin so 120 might be reasonable.

I think you need to do a review of the "stuff" in the Rv when actually loaded as you travel and you should be at tire and axle and vehicle max ratings or lower.
Good points. The first thing is to get tires with better head room. My wheels are good for 120psi and I don't see that as a problem. Next is to get rid of the useless stuff we have been dragging around. DW and I have had conversation about this. We have a base to work out of in WA at our son's home. Will take care of the weight issue there. I will get weighed again. I have shed some weight but who knows unless we are scaled again.

In your expert opinion, which tire is better? I am also considering the XZE 275/80 in the H range.

Thanks for your input. Makes me realize I am thinking in the right direction.

Rick Y
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Old 04-19-2015, 03:33 PM   #143
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Good points. The first thing is to get tires with better head room. My wheels are good for 120psi and I don't see that as a problem. Next is to get rid of the useless stuff we have been dragging around. DW and I have had conversation about this. We have a base to work out of in WA at our son's home. Will take care of the weight issue there. I will get weighed again. I have shed some weight but who knows unless we are scaled again.

In your expert opinion, which tire is better? I am also considering the XZE 275/80 in the H range.

Thanks for your input. Makes me realize I am thinking in the right direction.

Rick Y
Sorry I try and refrain from offering specific brand recommendations unless I have personally evaluated the options.
If you live in WA you may have access to open scales as they do in Oregon where you can do your weights for FREE and when using the worksheet HERE to get the facts.
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Old 04-19-2015, 04:24 PM   #144
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I was told by old truckers (this was years ago) that they put the used tire in the inside and the new tire on the outside. The reason for this was the smaller tire went inside to account for the crown of the road. Old wives tale - maybe but the roads generally have a slight rounding so having the smaller tires on the inside would apply a more uniform contact - if it is significant.
I checked with the expert at the local truck tire shop and he says he would put the newer tires outside too.
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Old 04-19-2015, 05:04 PM   #145
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please keep us posted as how it performs. i googled "cooper roadmaster complaints" and yield no real results. the pricing is tempting...
I just bought 2 Cooper Roadmaster RM120 All position and I have them on steer. No problem so far, seems to be smoother than Goodyear.

It says "Made in China" on the tires, but this is an American Marker.
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Old 04-19-2015, 10:12 PM   #146
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I just bought 2 Cooper Roadmaster RM120 All position and I have them on steer. No problem so far, seems to be smoother than Goodyear.

It says "Made in China" on the tires, but this is an American Marker.

What is the Cooper warranty?
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Old 04-20-2015, 08:24 AM   #147
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I don't think there is any warranty for cooper RV/truck type tires. The cooper warranty seems to only apply to passenger and light truck vehicles.

I did check other brands at twice+ the price, Michelin or Goodyear for example, that have warranty and found that you really have to read ALL the exslusions. Ozone or weather cracking on Michelin are excluded..., irrugular wear for Goodyear are excluded...
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Old 04-20-2015, 08:40 AM   #148
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Tireman9, if anyone has a handle on this topic I think wisdom would defer to you.

Here is my constant dilemma. (I am limiting my thoughts to my situation.) The tires on my coach, original, are running at max spec for load and pressure. (I know I need to address the coach load.) But, here is my confusion: I am in the desert. The morning temp may be 70* when I charge the tires to 110#, max psi. At 10 AM the temp may be 85* and I am doing 65mph. The operating psi may now be 120 or 125. What is happening to the tires?

This is just one of many questions. One at a time is best. Thanks.

Rick Y
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Old 04-20-2015, 10:05 AM   #149
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I just bought 2 Cooper Roadmaster RM120 All position and I have them on steer. No problem so far, seems to be smoother than Goodyear.

It says "Made in China" on the tires, but this is an American Marker.
thanks for the info. i tried to locate a vendor in my area but none carries it (big o tire does not have it). any clue where to find one?
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Old 04-20-2015, 11:35 AM   #150
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If your in an area with Les Schwab tire company they distribute Cooper Tires. Their corporate offices are in ElPaso but don't think they have tire centers that Far East.


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Old 04-20-2015, 11:45 AM   #151
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If your in an area with Les Schwab tire company they distribute Cooper Tires. Their corporate offices are in ElPaso but don't think they have tire centers that Far East.


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thanks!! looks like no les schwab in so cal
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Old 04-20-2015, 02:02 PM   #152
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I just bought a complete set of the Michelin XZA3+ MPM 39174's 275/80R22.5. Put 1100 miles on them and they ride really nice.
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Old 04-20-2015, 02:04 PM   #153
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I checked with the expert at the local truck tire shop and he says he would put the newer tires outside too.
Sorry but simply working at a tire store selling or mounting tires does not make one an expert on tire technology.
Tire companies point to matching the OC of tires as critical so as to not overload the larger tire which can result is excess heat and in extreme cases tire failure.
Duals need to be matched within 3/4" OC. Matching a worn (probably smaller) tire with a new tire (that will grow a bit in size with use over the first hundred miles or so) will result in the new tire running hotter for 2 reasons. One being deeper tread rubber and the other being that it is forced to carry a greater portion of the load.
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Old 04-20-2015, 02:12 PM   #154
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Tireman9, if anyone has a handle on this topic I think wisdom would defer to you.

Here is my constant dilemma. (I am limiting my thoughts to my situation.) The tires on my coach, original, are running at max spec for load and pressure. (I know I need to address the coach load.) But, here is my confusion: I am in the desert. The morning temp may be 70* when I charge the tires to 110#, max psi. At 10 AM the temp may be 85* and I am doing 65mph. The operating psi may now be 120 or 125. What is happening to the tires?

This is just one of many questions. One at a time is best. Thanks.

Rick Y
With perfectly dry air the pressure increases about 2% for EACH 10F increase in temperature. Moist air (from a shop that does not do air compressor maintenance) will grow a bit more maybe 3% or 4% depending.

So 70F > 85 = ~ 3% increase or 3 - 4 psi to say 114

Your operating temperature is probably another 20 since you are at max load for 114 + 3% = 117 plus 117 + 3% = 121psi

My suggestion is to get rid of some of the bowling balls in the collection you are carrying around.
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