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Old 08-16-2009, 05:37 AM   #1
berridge
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Trailer Tire Pressures

I would like some input/advice on what pressuers people run on their Montanas. I checked the Goodyear recommendations for the 235-80 16E tire as suggested in a previous thread. My 3075 loaded weighs about 12300 lbs and with about 2600 lbs on the hitch this would leave about 9700 lbs to be carried by the 4 tires. This gives an average of 2425 lbs per tire. To leave a safety margin I used 3000 lbs per tire. The Goodyear chart gives a pressure of 65 psi for this load. My question is does anyone run this low a pressure? The sticker on the trailer is no help as the maximum load pressure of 80 psi is given. Thankfully the auto/truck industry is better regulated and proper tire pressures for each vehicle must be given regardless of the tire maximum load rating. Hopefully the "tire guys" can shed some light on this important aspect of towing.
 
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Old 08-16-2009, 05:52 AM   #2
Clemson1881
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I've always felt that on a trailer with such a heavy load that I'll run the max pressure unless I see uneven tire wear. At max pressures I've always had fairly even tire wear, so I've never had to back it down. If I saw wear issues I'd back it down some at that point. Too many blowouts and failures out there to even think about running 65 PSI with that load. Give yourself all the safety margin you can. Just my opinion.
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Old 08-16-2009, 06:00 AM   #3
TLightning
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Quote:
quote:Originally posted by Clemson1881

I've always felt that on a trailer with such a heavy load that I'll run the max pressure unless I see uneven tire wear. At max pressures I've always had fairly even tire wear, so I've never had to back it down. If I saw wear issues I'd back it down some at that point. Too many blowouts and failures out there to even think about running 65 PSI with that load. Give yourself all the safety margin you can. Just my opinion.
Same here...80 psi.
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Old 08-16-2009, 06:08 AM   #4
firetrucker
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I use the load tables from the tire manufacturer and add 5 to 10 pounds, unless that takes me over the max pressure on the sidewall. Tires are like springs, and the higher the pressure, the stiffer the spring, and the more things will bounce around inside the trailer.

Bob
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Old 08-16-2009, 07:07 AM   #5
simonsrf
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We use 80 psi on aluminum wheels.
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Old 08-16-2009, 08:08 AM   #6
richfaa
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Observation.... We always keep our E rated tires at 80psi and have the TPMS to insure it stays there. We had to replace all four tires after @ 15K miles due to a "incident" We noted that all 4 tires showed signs of under inflation . That is here was slightly more wear at the outer edges that in the center. The wear was even on all tires.. We are still thinking about that and perhaps having the rig weighed at the Fall rallywill give us some ideas????
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Old 08-16-2009, 09:21 AM   #7
ols1932
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80 psi here, but then our rig is loaded.

Orv
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Old 08-16-2009, 09:49 AM   #8
firetrucker
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If tires are overloaded, it seems I've read someplace, you can get the same wear as when the tire pressure is too low (which means, in effect, the tires are overloaded).

Bob
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Old 08-16-2009, 12:02 PM   #9
Glenn and Lorraine
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Quote:
quote:Originally posted by berridge

I would like some input/advice on what pressuers people run on their Montanas. I checked the Goodyear recommendations for the 235-80 16E tire as suggested in a previous thread. My 3075 loaded weighs about 12300 lbs and with about 2600 lbs on the hitch this would leave about 9700 lbs to be carried by the 4 tires. This gives an average of 2425 lbs per tire. To leave a safety margin I used 3000 lbs per tire. The Goodyear chart gives a pressure of 65 psi for this load. My question is does anyone run this low a pressure? The sticker on the trailer is no help as the maximum load pressure of 80 psi is given. Thankfully the auto/truck industry is better regulated and proper tire pressures for each vehicle must be given regardless of the tire maximum load rating. Hopefully the "tire guys" can shed some light on this important aspect of towing.
Well Guys I hate to say this but berridge is pretty much right on the money and here's why....
Tires, like most manufactured products, are designed to operate within a specific load; this is called "tire load rating." On the sidewall of your tires you will find a rating for a single application and in some cases a dual tire application.
Each rating is accompanied by an inflation pressure that, if used, will give you the stated rating. This does not mean that this inflation pressure is correct for your trailer. Because RVs can be configured and loaded in various ways, inflation pressure must be set based on the load being carried by the tire it self, if you wish to achieve optimum life and performance from you tires.
For RV use, ideally, it is recommended weighing each axle end separately and using the heaviest end weight to determine the axle's cold inflation tire pressure. It is critical the tire pressures be the same across an axle, while NEVER exceeding the maximum air pressure limit stamped on the wheels.
The loads indicated in the Tire Inflation Chart represent the total weight of an axle end in an RV application. When one axle end weighs more than the other, use the heaviest of the two end weights to determine the unique tire pressure for all tires on the axle. The maximum cold air pressure for each axle may vary, depending on their weights.

Weighing each axle individually is how you get to the proper PSI you should be carrying in your trailer tires. BUT only if you will be traveling without changing the load in any way shape or form. Now if you weighed the axles with empty tanks but are traveling with a full freshwater tank everything changes. Because of this and other factors we seem to have settled on MAX Tire pressure of 80PSI. Is this correct? probably not. This September when I get to the Fall Rally I will have the rig weighed and at that time I will adjust my tires PSI according to the LI Chart.

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Old 08-16-2009, 01:42 PM   #10
richfaa
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Had a chat with the guys at Mor Ryde last week and they said what Glenn said. We will have the IS suspension intalled before we arrive at the rally and our weight will be a whole new ball game. We will use the weight figures we get there to set our tires pressue..
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Old 08-16-2009, 01:44 PM   #11
Delaine and Lindy
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I have never had my 5th wheels weight at each wheel. I have always run my tires what ever the side wall says. My Goodyear G rated 16" G614's were 110 lbs. I have never had a tire failure. I now have Goodyear H rated 17.5 and will run them at 125 lbs. This 5th wheel we picked up last week came with a sheet showing what each tire and each axle weight was. However once we loaded our stuff that changed the weight. It was interesting to see the different weight from each tire and each side and each axle. I'm sure no tire expert but I will recomend you run what ever your side wall says. Heat is the biggest factor in tire failure IMO. GBY.....
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Old 08-16-2009, 02:10 PM   #12
Glenn and Lorraine
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Heat is the biggest factor in tire failure Maybe, maybe not but over inflated tires keep the tread crowned giving you less mileage due to irregular treadwear. Over inflation also decreases traction needed for stopping especially in an emergency situation and the center of the tread may wear more quickly than the shoulder. Over inflated tires also create a rougher ride which is not only hard on the suspension but on the contents of the trailer as well.
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Old 08-17-2009, 05:26 AM   #13
akf15e
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I can confirm that I had excessive wear on my lighter weight 298RLS, which I ran at 80 psi all the time. The center of the tires wore far faster then the shoulders. Makes perfect sense that if you are overinflated for the weight you are carrying, the center will wear out faster.

My Montana is much heavier then my old Mountaineer, so I started out with 80 psi. But the chart suggests I run about 75 psi rather than 80 psi. I will back off a bit and continue to watch for uneven wear. Thanks Glenn!
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Old 08-17-2009, 11:04 AM   #14
sreigle
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So, what to do for those of us who have been unable to determine the weight on each axle separately and the weight on each wheel? Dividing total axle weight by four is not accurate enough to provide me with any level of comfort. That calculation gives 2992.5 lbs per wheel, or 3000 lbs. Someone on the prior page indicated Goodyear's chart says 65 psi for LR E tires in our size at that weight. I look at location of appliances in this rig and I just know there has to be differences in weight born by each of the tires. Thus, to provide a measure of comfort I run ours at 80 psi. So far, with these tires and the better axles, the tire wear pattern seems to be good.

Someday I'd like to have an opportunity to measure actual weight on each tire.
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Old 08-17-2009, 12:22 PM   #15
H. John Kohl
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I don't have, but will get the tire depth gauge. I saw David's (david and jo-anna) chart and depth gauge. That is the way to track and document what is happening. Now I just have for force myself to take the readings every 1000 trailer miles or so.
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Old 08-17-2009, 12:25 PM   #16
Tincup703
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I put on the Michelin XPS ribs last fall and run them at 80 psi...and with about 5000 miles on them they're showing no signs of any wear.

Me thinks we need to get out more!
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Old 08-20-2009, 11:28 AM   #17
berridge
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I think Glenn has the best advice re tire pressures and thank him for it. If any one does have each tire load measured I would appreciate having it posted. It would be nice to have an idea how much variation there is. I will go with 65-70 psi and keep an eye out for any abnormal tire wear. I'm sure that with proper inflation for the load that the tire will perform better. I think with all the failures with the Mission bombs many of us got spooked and went with the max pressure thinking it safer. I hope the Marathons will perform properly. Thanks for all the posts.
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Old 08-21-2009, 11:52 AM   #18
Red939
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We travel heavy and, although we have not weighed each tire separately, put 80 psi in all four and keep 80 in the spare.
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Old 08-22-2009, 07:01 AM   #19
richfaa
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A few of us will have those numbers at the fall rally.
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Old 08-22-2009, 08:55 AM   #20
richfaa
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Got me one of those fancy Milton tire tread depth guages today and have been fooling with it this aternoon. Been using pennies, dimes and quarters for years and find that was not the best idea. Have brand new tires in the 3400 so was able to get some good new tire readings. Find that we are running under inflated on the Ford front tires, The door sticker calls for 75psi but what does Ford know..Rich knows better so we have been running them at 65 psi for 25K miles...wrong.. under inflated by many 1/32's. The rear duallies are doing Ok...
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