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Old 05-10-2014, 07:31 AM   #1
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Posted tire pressure

I now have E rated tires on my 5er and the new tires have a 80 psi max posted on the tire yet my trailer sticker says 60 psi. I keep 80 psi in each tire and they stay nice and cool but they sure ride hard - comment.
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Old 05-10-2014, 08:14 AM   #2
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Why not start reducing the PSI in 5lb increments until you find the sweet spot that you like? If the load on the new tires is not such that you need the 80psi to handle it, then reducing the pressure some will not hurt the tire.
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Old 05-10-2014, 10:47 AM   #3
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Comment: Two pressures all but guaranteed to be the WRONG pressure are the two you cited (80 and 60 in your case).

A tire that is over inflated, as you noted, runs cool, but HARD The tread wears only in the center and under less than ideal road conditions it is easier to make 'em side slip (Loose control) Under Ideal I'm not sure.

A tire that is underinflated overheats and goes BOOM, Tread wears more on the edges than the middle and it's easier to loose control under ALL conditions. Of this I am sure,,, And I proved it. (Thankfully only minor damage).

Proper inflation requires you weigh the trailer, loaded, each wheel and adjust load to balance (this is important on trailers) and then inflate per weight.. HOWEVER.. that said.. i'd likely go with 65-70 in your case. (Split the difference) till I hit the scale.
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Old 05-11-2014, 06:24 AM   #4
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Quote:
Originally Posted by wa8yxm View Post
Comment: Two pressures all but guaranteed to be the WRONG pressure are the two you cited (80 and 60 in your case).

A tire that is over inflated, as you noted, runs cool, but HARD The tread wears only in the center and under less than ideal road conditions it is easier to make 'em side slip (Loose control) Under Ideal I'm not sure.

A tire that is underinflated overheats and goes BOOM, Tread wears more on the edges than the middle and it's easier to loose control under ALL conditions. Of this I am sure,,, And I proved it. (Thankfully only minor damage).

Proper inflation requires you weigh the trailer, loaded, each wheel and adjust load to balance (this is important on trailers) and then inflate per weight.. HOWEVER.. that said.. i'd likely go with 65-70 in your case. (Split the difference) till I hit the scale.
So how do you know what to inflate the tires to based on weight? Over inflation or under inflation will cause the tires to overheat which will cause damage. Inflate tires to the PSI on the tire sidewalls. If you have questions contact the tire manufacturer and ask. Ignore personal opinions. Those giving their personal opinions will not warranty your tires.
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Old 05-11-2014, 07:33 AM   #5
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The numbers on the tire always override the numbers on the trailer sticker.
An under inflated tire is a ticking time bomb. An over inflated gives you less side to side stability, runs harder (rougher) and wears uneven (in the center). If in doubt choose higher tire pressure but do not exceed rec. max. printed on tire sidewall.
Example: trailer weighs 10000#, ~1700# of that is pin weight. That leaves you with ~8300# on 2 axles or ~2075# load per tire.
If the max. weight capacity printed on the sidewall - lets say 2300# is and the max. rec. tire pressure 80psi that means with 2075# you are close to the max anyway you can go ahead and inflate the tires to the max. rec. psi.
This is just an example and not actual numbers, but that's how you do the math, and forget the trailer sticker.
Even the kids working at the tire shop often don't know.
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Old 05-11-2014, 07:48 AM   #6
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80psi.
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Old 05-11-2014, 08:17 AM   #7
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Posted tire pressure

The trailer originally did not have E rated tires and E rated tires carry more weight and higher pressure. Each tire is rated at a max of 2950 lbs and the empty weight of the trailer is 7550. I have not put the trailer on the scales but with a tank of water and loaded for a week I am guessing 9000lbs. My next trip next week to the Grand Canyon, Navaho Monument, Canyon de Chelly and Preston we will see how it rides with 80 lbs. The 60 psi is posted on the trailer sticker and was the psi on the old tires that came with the trailer. If the trailer does come in around 10000# that would be about 8300# on the tires and with each rated at 2950 carrying capacity should be no problem.

Another question, it seems trailer tires are rated for 65 mph, I usually run 62 with the cruise. I'm surprised the low mph rating I have other trailers blow me off the road!
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Old 05-11-2014, 08:40 AM   #8
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I believe trailer tires have more sidewall flex and could loose their stability at higher speed? Maybe a real tire expert knows the answer.
I also like to drive at just below 65mph that's where I get the best fuel mileage but fast enough to keep others from giving me the finger when they pass me .
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Old 05-11-2014, 08:41 AM   #9
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B.t.w. try to get your actual weights, it gives you peace of mind.
HWY scales are often closed on weekends but they do still operate and it's free
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Old 05-11-2014, 09:03 AM   #10
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when you weight your rig do you weight both truck and trailer, un hook from the trailer weight the truck by itself and subtract the difference - it to be the only way, I carry so much stuff in my tool box.
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Old 05-11-2014, 09:53 AM   #11
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Front axle truck then rear axle truck, gives you peace of mind for the truck.
Front axle truck, rear axle truck then trailer axles gives you everything else. All weights added gives you CVW (Combined vehicle weight). CVW minus front axle truck (FA) minus rear axle truck (RA) gives you the actual trailer weight. CVW minus FA minus RA minus trailer axle (TA) gives you the actual pin weight.
Good enough for me as long as everything is within it's limits.
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Old 05-11-2014, 10:28 AM   #12
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Quote:
Originally Posted by tucsonrv View Post
I now have E rated tires on my 5er and the new tires have a 80 psi max posted on the tire yet my trailer sticker says 60 psi. I keep 80 psi in each tire and they stay nice and cool but they sure ride hard - comment.
Under normal conditions the tire pressure listed on the certification label or tire placard is always going to be correct. If there are exceptions they will be found in the vehicle’s owner’s manual. UNLESS, the tires have been changed to another size/design or both. Then the tire pressure on the tire placard is used to set the new recommended tire pressure for the new tires.

Sixty psi is not a standard figure for any load range tires at maximum load capacity. However, older bias ply tires did have 60 psi load range D tires. In any event, to set the new recommended tire pressure look at the old tire and see what it’s maximum load capacity is for 60 psi. You will have to find a load inflation chart for thr old tire to do that. The new tire must equal the load capacity of the OE tire. Use a tire inflation chart for the new tire to find that figure. What that will give you is a tire equal in load capacity to the OE tires. To increase the load capacity, increase the tire pressure to a figure you are comfortable with and that will carry your heaviest load with some reserve load capacity.

One of the finer points those that advocate pressurizing to the highest loaded tire is the fact it will be maxed out. Not a very good practice with any tire used on trailer axles. Another more important point is to never use less tire pressure than what the load capacity of the OE tires provided.

That information follows tire industry standards. I can provide a reference on demand.

FastEagle


p.s. Sometimes ST tire manufacturers will require full sidewall pressures at all times and will void any warranty coverage if that parameter is not met.
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Old 05-11-2014, 01:15 PM   #13
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One note of caution: tire pressure shown on the trailer sticker applies to the tires installed at the time the sticker was affixed. After market tires do nothing to increase trailer payload or axle capacity no matter what size.
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Old 05-11-2014, 01:31 PM   #14
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Originally Posted by tucsonrv View Post
Another question, it seems trailer tires are rated for 65 mph, I usually run 62 with the cruise. I'm surprised the low mph rating I have other trailers blow me off the road!
The owners of those trailers; that blow you off the road; probably haven't read as much as you about the safe operation of their trailers/tires, or care for that matter. JMHO.
You are doing the right things, knowing your weights , tire specs, and controlling your speed.
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