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Old 07-17-2005, 08:34 AM   #1
sreigle
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Is there a ride differrence in LR D and E tires?

I know we have some tire experts out there so maybe someone on the forum can answer my question.

CountryGuy and Dustytuu have both described dish breakage problems in their rear kitchen 3295RK. We (and others) have not had problems with this despite having the same models.

Now, most Montanas come with Load Range E tires, max pressure 80 psi. Ours came with Load Range D tires, max pressure 65 psi. I know it's obvious there is less pressure in my D's than in your E's but there's also a tire construction difference. So, at max pressure, would a D ride more softly than an E? Enough to make a difference for the dishes riding in the back?

In case anyone wonders, the D's on ours are rated to 6,000 lbs at 65psi and the axles are 6,000 each. Actual scaled weight on the rear axles (combined) is 11,060 (pinweight 3,300). So the D's meet the specs and measured weight.

Thanks.
 
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Old 07-17-2005, 08:58 AM   #2
NJ Hillbilly
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I don't think the ride would be all that worse. I would opt for the "E"'s when You replace them just for the added capacity. The other thing is to make sure the rims are rated for 80psi also.
You can go to the tire mfg's website and see if there is a tire inflation chart. This chart would enable You to use the correct pressure for the load being carried. You may be able to run the higher rated tires at a less than max pressure and get a slightly better ride.

Then again You have to hold on the the trailer long enough to replace the tires ;}.


John
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Old 07-17-2005, 09:21 AM   #3
CountryGuy
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Steve,

Just to set the record straight, I never had dishes break, but they sure did move around a lot!!! They move very little now, with the improvements, including but not limited to the new Bilsteins and the Isolator.

Carol
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Old 07-17-2005, 02:00 PM   #4
ols1932
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Steve: My Montana came with load range E tires. Customer service told me that the only way to go if I wanted to change to a different load range, is up to F or G.I don't think you would get any different ride between the different load ranges. It's just that each load range allows a certain maximum weight to be carried.
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Old 07-18-2005, 04:38 AM   #5
drhowell
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My 2001 3280RL has the "D" range tires also. Other than uneven wear and some locked brakes (flat spots)when I purchased the trailer the tires had held up fine. I replaced two when I redid the suspension and had it aligned. I talked to the tire shop about the "E" and "D" rating etc and he said the "E" rating is usually on the "ST" (trailer) tires and has to do with sidewall stiffness. The "D" tires have more flexible sidewalls but still have ply ratings that handle the 6000 lb load per tire. He sees lots of big units with the "D" tires.

My 3280RL weighs 11910 loaded (unhooked) and the pin weight is 2680 with the trailer axles carrying 9230 when hooked. Rides smooth and nothing moves inside while towing. Well except for the time we forgot to check the fridge door lock after the grandkids opened it. Just happened to stop after about 30 miles to get something out of the trailer and found the fridge door wide open and some food on the floor. Nothing spilled and only a few items had hit the floor. NOTE TO SELF Double check the fridge door locks and be last one out of the trailer before we move.
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Old 07-18-2005, 05:52 AM   #6
sreigle
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LOL, Don. I can relate to that with grandkids although we haven't had that particular situation!

Thanks for all the excellent replies. I'll probably go with E's when we replace the tires just for the extra capacity. I wasn't sure if the stiffer sidewalls would affect the ride. We've had no problems with breakage and don't want to change that.

In the first 2 1/2 years with this Montana some of the tires were replaced under warranty (defects) and others one by one because of inside tire wear. I don't like to mix tires and just bought the same thing that was on there. Now that the axles are properly aligned and the tires are wearing well maybe we'll actually wear out this set of tires, although I want them to last as long as possible (cheap, cheap!) although they'll be replaced before the tread gets too low.
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Old 07-18-2005, 11:19 AM   #7
Glenn and Lorraine
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Quote:
quote:Originally posted by sreigle

I know we have some tire experts out there so maybe someone on the forum can answer my question.

CountryGuy and Dustytuu have both described dish breakage problems in their rear kitchen 3295RK. We (and others) have not had problems with this despite having the same models.

Now, most Montanas come with Load Range E tires, max pressure 80 psi. Ours came with Load Range D tires, max pressure 65 psi. I know it's obvious there is less pressure in my D's than in your E's but there's also a tire construction difference. So, at max pressure, would a D ride more softly than an E? Enough to make a difference for the dishes riding in the back?

In case anyone wonders, the D's on ours are rated to 6,000 lbs at 65psi and the axles are 6,000 each. Actual scaled weight on the rear axles (combined) is 11,060 (pinweight 3,300). So the D's meet the specs and measured weight.

Thanks.
Steve,
All things being equal you should not notice any signifcant ride difference between D and E rated tires. If your rig is loaded accordingly and your tire pressures set for the load being carried you shouldn't notice any difference.

BTW-Just because a tire is rated at a maximum inflation of 80 psi does not mean they should be inflated to 80 psi if the maximum weight for that tire is not met.
For instance the LT235/85R16 Load Range "E" tire at 80PSI has a MAX load capacity of 3042#. At 75 PSI the load cap is 2905# and at 70 PSI it's 2765.
The same size tire in load range "D" with an inflation of 65 PSI carries a max load of 2623#, at 60 PSI the load would be 2485 and at 55 PSI it's 2335.
So using your figure of 11,060# axle weight divided by 4 comes to 2765# per tire. Now using the above figures your max inflation would be 70 PSI on a LT235/85R16 Load Range "E" tire.

For truely proper inflation you need to know the actual weight being carried and adjust the air pressure accordingly.

BUT steve, other than load range "D" you did not indicate your actual tire size so I am not able to judge whether your numbers are correct or not.

Here is a PDF link to RV Load and Inflation Tables

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Old 07-18-2005, 11:50 AM   #8
sreigle
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Glenn, you were one of the ones I was referring to when I said 'tire experts.' Thanks for replying. The tires are ST235/80R16 LR D Goodyear Marathon. On the sidewall they say max 3000 lbs at 65 psi.

Does it hurt to run them at max even if not at max load? I always figured that way if they lose a little pressure for whatever reason I would likely catch it before they became underinflated for the load.

Total weight on the axles is 11060. I did not, unfortunately, weigh each axle separately nor each wheel separately, which should be done to determine best pressure, right?

Thanks.

Interestingly, the table in the link you provided, Glenn, shows a max speed rating of 65 mph on the ST tires. That's the first time I've ever heard about a speed rating on these tires. That should be a more prominent piece of information, I should think.
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Old 07-18-2005, 02:54 PM   #9
Glenn and Lorraine
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Glenn, you were one of the ones I was referring to when I said 'tire experts.' Thanks for replying. The tires are ST235/80R16 LR D Goodyear Marathon. On the sidewall they say max 3000 lbs at 65 psi.
Thanks Steve and Your Welcome but I am far from an expert. I haven't dealt with tires for a living for over 15 years. Most of my replys have been really testing my memory.

Does it hurt to run them at max even if not at max load? I always figured that way if they lose a little pressure for whatever reason I would likely catch it before they became underinflated for the load.
Actually Yes it does. You would be better off checking the pressures every so often than running them over inflated.
If your tires are overinflated by as little as6 psi, they could be damaged more easily when running over potholes or debris in the road. Higher inflated tires cannot isolate road irregularities well causing them to ride harsher.
When you over inflate you cause the center of the tread area to push out. This creates a problem of premature tire wear down the center of the tread area. Also it lessons the area of tread contact with the road. Less road contact equals less braking power.
An additional note--under inflation causes tread wear on the shoulders of the tire.

Total weight on the axles is 11060. I did not, unfortunately, weigh each axle separately nor each wheel separately, which should be done to determine best pressure, right?
Ideally yes knowing the load on each tire is definitely the best but realistically, as there should not be any significant difference, knowing the total weight on both axles and dividing by 4 will be just as effective.

Interestingly, the table in the link you provided, Glenn, shows a max speed rating of 65 mph on the ST tires. That's the first time I've ever heard about a speed rating on these tires. That should be a more prominent piece of information, I should think.
Now you have entered an area that I can't really help with. We did very little business with trailer tires and to be honest in my day I'm not sure there even was an "ST" designation. I did a search on "tire speed rating" but could not find any helpful info.
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Old 07-18-2005, 06:50 PM   #10
sreigle
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For clarification, are you using the term 'overinflated' to mean inflated more than the load calls for even if not exceeding the tire's max inflation rating? In other words, if the chart shows mine requires 60 psi but I'm using 65 psi (tires are 65 psi max) are you saying those tires are overinflated?

I check the tires before pulling out after each extended stay (a month or more) plus once each week to two weeks during shorter stays. I always make sure they are at 65 psi. They seem to be wearing nicely at this point, which is a big improvement over the days those tires wore excessively on the inside.

Thanks.
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Old 07-19-2005, 12:10 PM   #11
Glenn and Lorraine
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Overinflating is having a greater PSI than the load calls for.

In an earler reply, you indicated your axle weight is 11,060 lbs, divide that by 4 equals 2765 lbs per tire. Using the chart I linked to previously your ST235/80R16 LR D tires should be inflated to somewhere around 58 to 60 PSI. Therefore at 65 PSI they are overinflated by over 5 pounds.
The best way to check tread wear is with a Tread Depth Gauge which can be purchased at any auto parts store.
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Old 07-20-2005, 01:18 AM   #12
virgil47
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Glenn,

I am so glad you are part of this forum and are willing to share. I have learned so much from reading your replies. You (and Steve) are always willing to share when I have a question and I am grateful.
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Old 07-20-2005, 05:31 AM   #13
Montana_3956
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Someone mentioned wearing out their tires. I've ALWAYS heard that you will never wear out tires but need to replace them before you reach 5 years of age, some do it at 4 years. Have you ever seen a rig that had a blow out? It can cause major damage to your rig!
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Old 07-20-2005, 06:58 PM   #14
sreigle
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Glenn, thanks for all the great info. It has been enlightening.

KC4KM, we had one blowout but it was not on the Montana. It was on our 1999 Jayco Eagle 255BH. We were very fortunate a guy behind us passed and informed us of the blowout immediately after it happened so we were able to stop right away. We had no damage other than to the tire. Here's a picture of that blowout.


The rest of our tire problems have been defects that in most cases caused a tire to go down while we were parked in an rv park. But I've seen some of the damage a blowout can do. You are correct, a blowout can cause some expensive damage.
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Old 07-21-2005, 02:36 AM   #15
Glenn and Lorraine
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Quote:
quote:Originally posted by virgil47

Glenn,

I am so glad you are part of this forum and are willing to share. I have learned so much from reading your replies. You (and Steve) are always willing to share when I have a question and I am grateful.
Well thank you Virgil & Jo. I do what I can to help this great [s]forum[/s] family. I garnered some knowledge during my many years in the wholesale/retail tire business and I am glad that I can share this info with others without expecting them to buy a set of tires. I have been away from the business for a number years and never thought I would end up using my tire knowledge in cyberspace.
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