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Marathon tire pressure


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I just installed 225 75 15 Goodyear Marathons on my single axle trailer. My boat weight is around 2600 lbs. and my trailer around 1200 lbs. I am a little confused about the pressure I should run. This is the chart from Goodyear, is it total weight or divided by 2.

http://www.goodyear.com/rv/pdf/rv_inflation.pdf

If it is divided by 2 then it looks like I should run about 45 psi. I have seen posts where people say they run 65 psi. What are your thoughts on this? I live on the gulf coast, in the summer we average 90 degrees, so they will get pretty hot, although I do not have but about 20 miles to the launch.

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Well I have herd that the higher pressure you run the higher temp the tires will run at.

But I have a '93 Echelon LX with a SMP tandem with I believe the same goodyear tires. I usually run the tires at 30 psig and have had no problems.

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Well I have herd that the higher pressure you run the higher temp the tires will run at.

But I have a '93 Echelon LX with a SMP tandem with I believe the same goodyear tires. I usually run the tires at 30 psig and have had no problems.

I believe the opposite is true. If you have less pressure, your sidewall will flex more ("curved" at the bottom and "flat" at the top of the revolution..if you know what I mean) This increased flexing 700 times (roughly) per mile generates more heat, kind of like bending a piece of metal back and forth rapidly.

Underinflation was believed to be a culprit in the Ford Explorer blowouts.

If your Marathons are load range D, then the proper cold inflation would be 65 psi cold. If they are load range C (they make them in that size, both load range C & D) then the proper pressure woudl be 50 psi cold.

Edited by rts
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I'm at 45-50 psi although they're probably at more like 30 psi most of the time since I don't pay attention to the tire pressure when I'm only going a mile from the storage garage to the launch ramp ;)

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What RTS said....

I have load range C 215-75-15 and run at 50 PSI cold. My boat/trailer are about 90% of max capacity for the tires. I tow a couple of thousand miles a summer.

The only issue with running too high of a pressure for the tires is possibly some premature wear in the center of the tire. You don't need to worry about traction as much with your trailer tires (hopefully you're not towing in a manner that you'll need to work as much about it) as you would on your car tires..

Don't forget fuel/gear...

That sounds heavy for a SA trailer - most are in the 600-800 lb range. TA trailers are usually in the 1200-1400 lb. range.

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I would inflate them for the max load as posted on the side of the tire. You'll get better gas mileage towing with a higher tire pressure. Have you ever tried to hand push a trailer with under inflated tires? Cry.gif

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Edwin is right on the money. I e-mailed Goodyear corporate, and one of their staff called me back. He said run the max pressure listed on the tire, in my case 65 PSI. He said do not worry about the tire heating while pulling and no need to worry about putting hot tires in cold water. As far as the 65 mph rating, he said that is pretty much an industry standard, pulling at higher speeds is no problem at all, other that the safety factor of pulling a trailer too fast. The resources of information on this site are great. Thanks everyone.

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I would inflate them for the max load as posted on the side of the tire. You'll get better gas mileage towing with a higher tire pressure. Have you ever tried to hand push a trailer with under inflated tires? Cry.gif

You ever tried to hand push with full pressure tires? Sucks either way.

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I would inflate them for the max load as posted on the side of the tire. You'll get better gas mileage towing with a higher tire pressure. Have you ever tried to hand push a trailer with under inflated tires? Cry.gif

You ever tried to hand push with full pressure tires? Sucks either way.

When I was a boy, we had to hand push our trailer all the way to the lake. Uphill both ways. Back then, we didn't have none of them steer-belted redials, neither.

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When I was a boy, we had to hand push our trailer all the way to the lake. Uphill both ways. Back then, we didn't have none of them steer-belted redials, neither.
:unsure: Jack, when you were a boy they hadn't invented boats yet either. Crazy.gif

Heck, they had just recently discovered water... ROFL.gif

Tongue.gif

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Run them at max inflation. I do the same thing with the tow vehicle. The tire's max load is at 45 psi and that is what I run.

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Run them at max inflation. I do the same thing with the tow vehicle. The tire's max load is at 45 psi and that is what I run.

Do you find that the center of your tires wear prematurely? In the tow vehicle, I'd run what is placarded from the vehicle manufacturer or you risk uneven wear.

The same may or may not be true for all tires, but if you have a car with high performance tires, and want to really know the proper inflation for your car/tire combo, look at the side wall where it meets the tread. You should see little symbols around the circum. of the tire. Michelins have a little Michelin man, Dunlops have a little triangle, etc. These symbols mark the spot on the tire that should contact the road.

To get the ideal tire pressure, you inflate the tires beyond the recommended pressure, get them up to temp (a mile should do it) and find an empty parking lot. Then take some white shoe polish and run a line across the tread and down the sidewall over one of the symbols and drive around the parking lot, turning back and forth sharply then see if you've scrubbed the polish to the right place (the symbol) Then you let a little pressure out of the tire and repeat until you are barely scrubbing the polish off the symbol. Then let your tires cool and take the pressure reading and you have your proper cold inflation for your car/tire combo. Piece of cake.

For my car, they recommend 36 rear and 32 front. After I did this procedure, I found the ideal pressure to be 34 rear and 31 front, but it's not on stock tires, so I figure that's the difference. My craftsman truck racing buddy told me about this.

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When I was a boy, we had to hand push our trailer all the way to the lake. Uphill both ways. Back then, we didn't have none of them steer-belted redials, neither.
:unsure:Jack, when you were a boy they hadn't invented boats yet either. Crazy.gif

Heck, they had just recently discovered water... ROFL.gif

Tongue.gif

Yeah, yeah, yeah. Well, when you were a boy. . .oh wait. . .you still are. Tease.gif

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My craftsman truck racing buddy told me about this.

Very cool. Fun facts to know and tell. What about Goodyear or Bridgestone? Do they have a mark?

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